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Evidence Collection and Laboratory Analysis

GENERAL EVIDENCE COLLECTION GUIDELINES

Before evidence is collected:

  • Make sure there are no suspected devices that have not functioned, firearms, needles, drug paraphernalia, or blood or other body fluids from injured or deceased persons at the fire scene. If any of these items are present, obtain expert assistance prior to attempting the collection of dangerous materials. Never collect an unexploded device; clear the area and call the bomb squad. Never collect explosive chemicals or substances; clear the area and call the bomb squad.
  • Always photograph the item "as found" first, before touching or collecting it.
  • Always note the item and its location, measured from two or more fixed objects in the room, on your scene diagram.
  • Whenever possible, consult a qualified Evidence Collection Technician to process potential or known crime scenes and collect physical evidence.

When collecting evidence, observe a few simple overall rules:

  • Do not restrict your search inside the scene; evidence can be found in other places on the property or in the neighborhood.
  • Always be sensitive to cross-contamination and spoliation issues.
  • Always wear latex gloves to collect evidence.
  • Always use clean, suitable, and unused containers.
  • Always let wet items, including organic fluids such as blood or semen, dry before packaging.
  • Always package evidence in a fashion that will preserve it for laboratory testing.
  • Always label properly.
  • Always change gloves between items.
  • Always clean tools between items.
  • Always keep evidence in a secure location on the scene.
  • Always maintain the chain of custody.
  • For all items, collect a comparison sample if you wish a comparison to be done between a known and a questioned item.

Beyond these general rules, the collection method depends on the type of evidence. Select a type of evidence below:

Body Fluids

Cigarettes

Explosives

Fabrics and Textiles

Fiber

Fingerprints

Fire Debris & Accelerant

Firearms

Food, Drug, and Plant Specimens

Glass

Hair

Impressions (Footprint, Tire Prints, Toolmarks)

Ink

Liquids and Thick Liquid Substances

Metals

Paint

Plastics, Adhesives, Asphalt, Tar, Waxes, Grease, and Oils

Questioned Documents and Paper/Cardboard

Soil

Tape

Wood

Recovery of Evidence from Victims


Body Fluids

Blood and other body fluids can be examined for species, race, sex, type, DNA, and other characteristics. Comparison of questioned to known is also possible. The following guidelines for the collection and preservation of questioned blood, body fluids and tissues are included here as a general reference; the investigator should get precise instructions on handling serological evidence from a certified crime scene technician or from the serology section of their jurisdiction's forensic laboratory or the ATF or FBI National Laboratories.

Collection

1. Document any body fluid patterns, spatters, stains, pools, drops, and the like with close-up scaled photographs and medium distance context-establishing shots.

2. Any item or material bearing suspected blood, semen, saliva, other body fluid stains or tissues must be allowed to air-dry at room temperature prior to packaging; exposure to direct sunlight and/or heat should be avoided. Failure to ensure complete drying of such samples may result in their putrefaction and loss.

3. Use cleaned tweezers or other tool to remove the body fluid-stained item. Package each item individually in an air-permeable but otherwise securely closed container such as a paper bag. Fragile substrates such as glass should be carefully wrapped in paper and securely packages to avoid (further) breakage.

4. Label and seal the container properly, including your name, date, description, and exhibit number. Consult your jurisdiction's forensic laboratory or a certified national laboratory for instruction on refrigeration of samples.

5. If the stain is on a substrate which is too large to submit intact, either cut away the section of the surface bearing the stain, or dismantle the object to recover and submit the stained portion. Collect according to steps 2 through 4.

Sufficiently copious bloodstains on an immovable substrate may be scraped off with a clean knife or razor blade and collected into glassine or clean white paper, folded pharmacy-style to prevent leakage, and placed into a paper envelope. Do not collect scrapings directly into envelopes. If you are collecting multiple samples, each must be collected with a clean tool. Label the container(s) according to step 4. Retain and package the tools used to collect the scrapings.

6. If the stain is encrusted on the surface of soil or sand, remove the crusts and place into separate paper pillboxes; then collect the bulk stained matrix in paper ice cream-type containers.

If moist blood is available for collection, such as from a pool on a tile floor, use a clean dropper to collect as much as possible (up to 10 cc) into a glass vial. Add an equal volume of isotonic saline solution (0.9% sodium chloride) to the vial. Seal and label the vial as described above. Or, you may soak up the moist blood with a new, sterile gauze pad, air dry the gauze pad, then collect the gauze pad as described above in steps 2-4. Biohazardous material should be marked as such before it is sent to the lab.

For instructions regarding the collection and submission of known blood, saliva, or tissue samples for comparison in a specific case, please telephone the ATF laboratory or your local laboratory. Depending upon the type of evidence involved, the analyses to be undertaken (traditional serology or DNA), and the particular laboratory to which the evidence will be referred, known sample collection and preservation requirements may vary.


Cigarettes

Cigarettes are occasionally employed as delay devices in the firing trains of flame-ignited incendiary devices. The butts of smoke cigarettes may be encountered as evidence of activity in an environment of interest. Cigarette butts may be identified with respect to the brand, strength, flavor, length, packaging, and possibly manufacturer and time period of manufacture. Cigarettes may also bear fingerprints, saliva, lipstick and cosmetic residues, and other trace evidence. To ensure preservation of this additional trace evidence, the following steps should be taken in collecting and packaging cigarette evidence:

Collection

1. Document any cigarette butts and their locations using photographs.

2. Individual cigarette butts should be recovered and packaged separately from other ash and debris.

2. If damp, the recovered cigarette should be allowed to air-dry at room temperature prior to packaging.

3. Air-permeable paper envelopes (not plastic bags) should be used to contain recovered cigarette evidence, in order to preserve any residual saliva and/or fingerprints.

4. Label and seal the envelope properly, including your name, date, description, and exhibit number.

5. Collect any comparison standard you will need for testing.


Explosive

Explosives evidence should be handled by a member of the bomb squad or a Certified Explosives Technician. In general, suspected components, wrappers, and debris from a device that has completely functioned can be collected individually with clean tools and placed in clean, unused metal cans. The cans should be labeled, including your name, date, description, and exhibit number, and sealed. Take care to stabilize and preserve the items for possible fingerprint and trace analysis. Unused or non-functioned explosives must be handled, collected, packaged, and transported by someone with expertise in explosives investigation. Do not handle potential explosives yourself. Clear and secure the area and contact the bomb squad.


Fabrics and Textiles

Class characteristics like comparison of color and colored images, construction (yarn plies, woven or knitted, seams), and composition (fiber content) can enable the association of questioned and known textiles. Fabrics can be analyzed for fragmentation line comparison to known samples.

Collection

1. Document any fabric evidence and its locations using photographs.

2. For large items like upholstered furniture, take care not to loosen any trace materials when cutting away the cloth for sampling. Cut well away from areas of interest and carefully fold the fabric inward, protecting any torn edges. Place the fabric in an air-permeable, but otherwise secure, container like a paper bag. Remember to dry all wet surfaces before packaging. Do not use plastic bags or bottles for any material which may contain petroleum.

3. For very large items like mattresses and entire chairs, package intact in large crates or boxes, making sure they are dry first.

4. Look carefully for small items of fabric throughout the scene, in entrances and exits, on jagged surfaces that might induce tearing, and on victims. Search for imprints of fabric weave in painted surfaces or on objects. Take care to preserve the impressions. Collect any small articles carefully with clean tweezers, protecting torn edges. Allow to dry before packaging. Place in small containers like a glass vial, but do not fold so threads are not distorted.

5. For all items, label and seal the container properly, including your name, date, description, and exhibit number.

6. Collect any comparison standard you will need for testing.


Fiber

Fiber analysis begins with identification of the fiber type, animal fibers (i.e., wool, silk, rabbit, goat), vegetable (i.e., cotton, linen, ramie, jute, sisal), mineral (i.e., asbestos, glass), and synthetic (i.e., nylon, polyester, acrylic, olefin). The examiner will also typically attempt to suggest the possible origin(s) of the recovered fibers and possibly the manufacturer. Class characteristics like color, morphology, and composition can also be discerned and can demonstrate that the known textile could be the source of the questioned fibers.

Collection:

1. If possible, collect the entire item with the fiber on it and let the laboratory remove the fibers. If this is not possible, remove fibers from surfaces with clean tweezers. Take care not to crush the fibers with tweezers when handling it.

2. Place the fiber in a pillbox or a folded piece of clean paper, taking care not to kink or crush the hair.

3. If you use an evidence sweeper (vacuum), remove the material that accumulates in the filter and the filter paper and place it in an evidence bag. Do not use envelopes for packaging filter sweepings or for other very small materials.

4. Seal (making sure there are no holes) and label the container, including your initials, the date, and the exhibit number.

5. Collect a comparison sample, if needed (see below).


Fingerprints

The sophistication of analysis of evidence for fingerprints is advancing quickly. Many items that prints could not be lifted from in the past, such as burned items, can now be analyzed. It is recommended that the investigator consult a qualified Evidence Collection Technician to help preserve or develop latent prints, as well as stay abreast of the latest developments in fingerprinting (polylights, lasers, etc.).

Generally, latent fingerprints on non-porous materials deteriorate rapidly upon prolonged exposure to conditions of high temperature and humidity; consequently, they should be collected and forwarded to a lab as soon as possible. Once the object bearing latent prints is secured by wrapping or bagging, insure that it is well protected from frictional contact in order to prevent the prints from being smeared or obliterated. For all fingerprint evidence, you will want to collect a comparison sample, if possible, and package it in a clean, stiff envelope marked with your name, date, description, and exhibit number, and sealed.

Collection

For all types of surfaces, fully photograph the item first.

Fingerprints on Absorbent Materials

1. Do not handle the material with your fingers and do not attempt to develop the fingerprints yourself.

2. Place the paper or other absorbent material in a plastic bag or cellophane protector.

3. Label and seal the bag properly, including your name, date, description, and exhibit number.

Fingerprints on Hard Surfaces (Plastic, Metal, Glass, etc)

1. You may dust for latent fingerprints. Remove developed prints with lifting tape and place the tape on a 3" x 5" card which contrasts in color with the dusting powder used. Mark the card with your initials, the date, and an exhibit number. Place the card in an envelope and seal it.

OR

2. You may collect the item and send it to the lab for fingerprint developing. Collect the item with a clean tool (do not use your hands) and place it in a container proper to the type of item (such as a nylon bag), minimizing rubbing against any surface. Label and seal the container properly, including your name, date, description, and exhibit number.

Fingerprints on Soft Surfaces

1. Carefully remove putty, caulking compound or other soft material bearing visible fingerprint impressions. Leave as much excess material surrounding the fingerprint as possible. Take care not to touch or distort the fingerprint.

2. Glue the mass of material to a stiff section of cardboard that is marked with your initials, the date, and an exhibit number.

3. Tape a protective cover over the specimen, such as a paper cup or glass jar.

4. Place the cardboard and covering container in a larger container, such as a box and secure.

Note that since adhesive tapes may bear fingerprint impressions on both sides of the tape and may require expert care in delayering, removal, and processing, you should collect the tape sample in the condition found when recovered, i.e., by cutting out a section of the substrate that includes the tape and collecting the entire piece.

Fingerprints on Skin

When a victim has been grasped firmly on the neck, arms, thighs, or other clean, dry, hairless parts of the body, the possibility exists that fingerprints may be recovered from the affected skin areas. Do not wash or disturb the affected areas prior to processing. Success is critically dependent upon expert processing as soon as possible after initial contact between the assailant and the victim.


Fire Debris

Collect a comparison control sample when the substrate of the debris is chemically similar to an accelerant (such as roof tar, certain adhesives and certain floor waxes).

Collecting Accelerant Evidence

Accelerant and debris containing accelerant residue collection methods below are excerpted from A Pocket Guide to Accelerant Evidence Collection, 2nd Edition, (1999), and appear courtesy of the Massachusetts Chapter IAAI.

Types of Accelerant Evidence

Accelerant container. If evidence of ignitable liquid accelerant use is identified, always search for the container. Latent fingerprints can often be developed even on scalded or sooty containers. Containers are often found at the end of a pour pattern, thrown back into the "trailer," onto the roof above the egress, into a rubbish disposal, in nearby vegetation along the escape route or may be found in the suspect's vehicle or house.

Plants and trailers. Many arsonists "trail" an ignitable liquid accelerant pour from a "plant" (large concentration) across a floor toward a secluded building exit or interior barrier to make ignition and escape safe, therefore:

  • Begin your search for evidence by looking for objects that do not seem to belong.
  • Concentrate the search for ignitable liquid accelerant - evidence indicators beginning where any suspected accelerant container was found, or from any possible egress concealed from view and leading back towards the areas of greatest damage.
  • Concentrate the search for remains of the ignition device (matchbook, etc.) at or near the most probable egress point or barrier.
  • The best ignitable liquid residue samples are often found around the point of origin; the best physical evidence proving a forcible entry is usually at the point of entry itself.

Collecting Questioned or Known Accelerants and Debris that May Contain Accelerant Residue

1. Select an Evidence Collection Area

The major accelerant residue evidence collection skill is knowing what to collect and what not to collect. Ignitable liquids used as accelerants burn better than most of the surfaces onto which they are poured. Expect to find better, stronger samples in protected areas and inside absorbent materials within the pour pattern.

Most Desirable Collection Areas

a. Lowest areas and insulated areas within the pattern.

b. Samples taken from porous plastic or manmade fibers.

c. Cloth, paper, cardboard in direct contact with the pattern.

d. Inside seams, tears, cracks.

e. The edges of burn patterns.

f. Floor drains, bases of load-bearing columns or walls.

Least Desirable Collection Areas

a. Deeply charred wood.

b. Gray ash.

c. Edge of a hole burned through a floor.

d. Samples from absolutely nonporous surfaces.

e. The center of any burn pattern.

f. In general, areas exposed to greatest hear, hose streams.

2. Select Tools and Clean Them.

Once you have selected an area for sampling, clean your tools and turnout gear before you bring them into the fire scene and clean again between samples. Concentrated liquid dishwashing detergents effective at dissolving grease, including Ultra Dawn Concentrated Dishwashing Detergent, have also been found effective in dissolving ignitable liquid residue on steel tools when scrubbed with a clean scrub brush and flushed with clean water. Note that ignitable liquids derived from crude oil are generally not soluble in water alone. Be sure to submit a sample of the liquid detergent to your forensic laboratory to ascertain its properties and ingredients. If investigators have an accelerant detection canine or sensitive hydrocarbon detector available consider using it to double-check the tools after cleaning and prior to use.

The Pocket Guide to Accelerant Evidence Collection 2nd Edition (1999) from the Massachusetts Chapter IAAI, recommends that fire investigators use steel blade tools (shovel, hoe, brick trowel, chisel, etc.) and squeegees with hard rubber blades for excavation and ignitable liquid evidence sampling. In addition, some types of common equipment (bristle brooms) and safety gear (firefighter gloves) probably cannot be cleaned once contaminated with ignitable liquid residue. Always use latex gloves to process evidence.

3. Select an Evidence Can

It is recommended that fire investigators carry a supply of both one-quart and one-gallon "paint style" evidence cans, or their equivalent, in which to store residue samples. A good housekeeping practice is to take a new, sealed one-quart can and place it into a one-gallon can and seal that before placing it in your vehicle or kit. This saves space and prevents contamination. Open the cans just prior to physically collecting the sample at the collection site.

4. Collect the Sample

Photograph any pour pattern before sampling it.

Gently, remove debris by layer from the floor, keeping in mind that absorbent materials laying flush on the floor within the suspected pour burn pattern, such as acoustical tile or drywall, may present outstanding sampling potential, as do other absorbent materials sitting on the floor (e.g., stacks of laundry, boxes, newspapers).

Consider the fact that floors are seldom built perfectly level. Also, human and machine traffic patterns create wear depressions over time. People tend to walk or move supplies down the center of a narrow staircase or corridor and along the right edge of a wide corridor or staircase. Any area where consistent impact occurs, such as at the base of a staircase, is also likely to become locally depressed from wear over time. Liquids tend to flow to, and pool in low areas. For best results, sampling strategies should take these things into consideration.

Conceptualize how the scene was constructed and what objects and materials were in the area where the ignitable liquid was poured. An interview with the person who is most familiar with the area of origin's pre-fire layout is a recommended preliminary step to prepare for an origin and cause examination along with construction of a detailed map of the suspected area of origin & showing the room shape, windows and doors and major appliances, contents or furniture.

Assemble all collection and documentation equipment into a crime scene headquarters convenient to the area of origin. Clean all tools before going into the area of origin and between evidence collection sites. Wear latex gloves when physically handling evidence. Change gloves as required between evidence sampling sites. Limit scene access to evidence collection personnel. Wear appropriate eye protection.

Suggested collection procedures for seven common floor types.

5. Package and Label the Ignitable Liquid Residue Evidence Container

Accelerant residue sampling at a fire scene can be done in a way that maximizes laboratory identification of accelerant residues. Most of the laboratory procedures involve testing "headspace" vapor in various ways. Headspace is the zone inside a sealed evidence can between the top of fire debris and the bottom of the lid. Fire/arson chemists generally recommend that evidence containers be filled to two-thirds volume with debris sample, leaving the top one-third volume as empty, air headspace.

To achieve the best laboratory results, samples suspected of containing ignitable liquid residue should always be collected and packaged into an evidence can in a way that permits volatiles to migrate and gather in the head space. Following a few basic procedures at the fire scene will facilitate this process.

Always place the evidence label on the side of the evidence container and not on the lid. Sometimes evidence can lids are removed in the laboratory and could be mixed up with another container.


Firearms

Weapons

If a weapon is found at the scene, a qualified Crime Scene Evidence Technician or ballistician should be contacted. Weapons should not be handled. The investigator should assume that any weapon is loaded.

Gunshot Residue

Do not collect residues if a .22 caliber weapon was used, if more than six hours have elapsed since shooting, or it the subject has washed his or her hands.

Collection

1. Put on latex gloves.

2. Moisten two cotton swabs in dilute (5%) nitric acid and thoroughly swab the back of the suspect's right hand.

3. Place swabs in a plastic bag and label with your initials, the date, and an exhibit number. Do not place swabs in glass vials.

4. Repeat the above process for the right palm, the back of the left hand, and the left palm of the suspect's hands.

5. If use of a rifle or shotgun is suspected, swab facial cheek area--right and left.a

6. Take a control sample by moistening a swab with dilute acid and placing it in a bag marked control swab.

If spent casings are available, they may be swabbed on the inside using plain water, not acid, and the swabs packaged separately and properly marked.

Package articles of clothing to be tested for gunshot residue separately in plastic bags, properly labeled with your initials, date, and exhibit number.

Ammunition can also be forwarded to the laboratory, packaged properly for transport.

Spent Bullets

1. Remove the spent bullet from the object with a clean tool, leaving a layer of extraneous material surrounding it.

2. Wrap each bullet separately in cotton and place it in a separate non-breakable container.

3. Seal and label the container, including your initials, the date, and the exhibit number.

Do not scratch the outer surface of the bullet while removing it from an object. Do not scratch the sides of the bullet with identifying information.

Spent Cartridge Cases, Shotgun Shells and Wads

1. Do not mark the base or the sides of the casing or shell.

2. Wrap the casing or shell in cotton and place it in a small plastic bag or paper envelope. each casing or shell should be wrapped separately.

3. Seal and label the container, including your initials, the date, and the exhibit number.


Food, Drug, and Plant Specimens

Be careful to prevent contamination among the specimens or from other sources. When collecting comparison samples for liquids, food, or pills, search the building for like material. Do not remove these samples from their original containers. Seal them in clean (sterile if possible) second containers. Refrigerate samples as necessary to retard further growth of microorganisms and deterioration. Expedite delivery to the laboratory.

Collection of Liquids

1. Try to collect a minimum of one pint of the specimen in a leak-proof, nonreactive container like a glass jar.

2. Seal and label the container, including your initials, the date, and the exhibit number.

3. If the container is breakable, wrap it carefully and mark it "Fragile."

4. Collect a comparison sample if possible.

Collection of Plant Material

1. Dry the sample by spreading it on brown paper for at least 24 hours.

2. Place dry sample in a pillbox, a vial, or other container and secure with adhesive tape.

3. Weigh contents if possible.

4. Seal and label the container, including your initials, the date, and the exhibit number.

5. Collect a comparison sample if possible.

Take care not to mix samples. Package each separately to avoid mixing during mailing. Avoid destroying plant structure.

Collection of Powders or Solids

1. Place in a container such as a pillbox or vial. Secure with tape.

2. Weigh contents if possible.

3. Seal and label the container, including your initials, the date, and the exhibit number.

4. Refrigerate samples as needed.

5. Collect a comparison sample if possible.

Do not add preservatives to solid food samples.

Collection of Tablets and Capsules

1. Place in a container such as a pillbox or vial. Secure with tape.

2. Make an accurate count of contents and identifying marks.

3. Seal and label the container, including your initials, the date, and the exhibit number.

4. Refrigerate samples as needed.

5. Collect a comparison sample if possible.


Glass

Glass fracture patterns are unique; and fractures caused by impact, heat, high-velocity projectiles, and glass cutters may each be distinguished. Laboratory examination of recovered shards may reveal the direction and sequence of breaking forces or the type of projectile and its angle of penetration. Pieces of glass may be fitted together such that a recovered fragment can be identified as having been broken from a specific pane, bottle, or headlight to the exclusion of all others.

All glass, except small fragments, may contain latent fingerprints and should be handled accordingly. In addition, fragments can be analyzed to determine the way in which they were broken. Thus, preserving edges is very important. Completely photograph all glass fragments, in context and as they were found, before collecting them.

Comparison samples for glass should come from an area as near as possible to the point of impact. Wrap and label fragments and described below, noting whether they were found inside or outside.

Glass fracture examinations undertaken to determine the direction of force or the presence of a physical match depend upon careful evidence collection and packaging:

1. Prior to collection, pieces of glass found remaining in a broken window should be marked as to inside, outside, top, and bottom; submit all available glass so that the pieces can be fitted together to determine the point of impact.

2. Submit all reconstructible pieces of a broken glass object to increase the likelihood that any subsequently recovered questioned piece can be physically matched to the broken object.

Collection of Large Fragments

Dust fragments for latent fingerprints and submit prints as per Fingerprints section OR collect the entire fragment and package. To collect the entire fragment:

1. Use tweezers or a similar tool to collect the glass. Exercise care in protecting the edges and avoiding scratching the surface.

2. Thin protruding edges can be protected against breakage by wrapping in a soft material like modeling clay.

3. Wrap each piece separately and securely in cotton and place in a sturdy container, like a box, with a tight-fitting lid. Avoid the use of paper envelopes to contain loose pieces of glass.

4. Package questioned pieces of glass and known pieces of glass separately.

5. Seal and label the container, including your initials, the date, and the exhibit number. Note on the label any identifying information about where the glass was found.

6. Collect a comparison sample, if needed.

Collection of Small Fragments

When a glass window is broken, glass particles rebound up to ten feet or more toward the direction from which the force is applied, and thus may shower onto the hair or clothing of any individual within range. Glass particles can also become embedded in the objects or projectiles used to break a window.

Glass particle examinations are based upon optical, density, and elemental analyses by which the possible source(s) of a questioned glass fragment may be suggested and the comparison of questioned glass particles with known glass samples may be undertaken. In the absence of a physical match, glass may be associated on the basis of its physical and chemical class characteristics.

Because glass exhibits variation in its physical and chemical properties, and because the range of this variation within a single glass object may itself be great or narrow, the collection of adequate and representative known glass samples for comparison with recovered particles is of considerable importance:

1. Submit all glass available from a broken glass object. If several panes of a window have been broken and it is not necessary to determine the direction of breaking force, submit a few pieces of each broken pane; package the evidence collected from each pane separately.

2. Thoroughly comb a suspect's hair to recover glass particles, check for fragments in any wounds he/she bears; collect the suspect's cap, shirt, pants, socks, shoes, and other items of clothing and package each separately. Wrap articles containing glass carefully in clean paper or plastic bags.

3. Use a pillbox or vial to package small glass fragments and particles recovered from a suspect or scene; avoid the use of envelopes. Use tweezers or a similar tool to collect the glass. Exercise care in protecting the edges and avoiding scratching the surface. Do not pack articles containing microscopic fragments in cotton or other soft protective materials.

4. Wrap larger fragments individually and package securely.

5. Package questioned pieces of glass and known pieces of glass separately.

6. Seal (making sure there are no holes) and label the container, including your initials, the date, and the exhibit number. Note on the label any identifying information about where the glass was found.

7. Collect a comparison sample, if needed.

Other evidentiary materials remaining at the scene of a broken window may merit collection: putty/glazing compound; paint; wood (either as substrate for prying/cutting toolmarks or as transferable splinters); metal (substrate for toolmarks); blood and/or hair.


Hair

In explosives, arson, and firearms-related investigations, hair examination and comparison may provide leads and/or associations. Human and other mammalian hairs may be recovered from between layers of tape on a device, from sweepings of a vehicle or storage area, from the inside of a face mask left at a scene or found with a weapon, or from among clothing fragments used as a Molotov cocktail wick. Hair is resistant to biological decomposition and to displacement from textile substrates onto which it has been transferred.

Recovered hairs are first characterized with respect to species of origin. Then, human hairs are further categorized as to their racial and somatic (body area) origin; and their approximate length, color, and any observed cosmetic treatments. Race is classified anthropologically into Caucasoid (Indo-European), Negroid (African), and Mongoloid (Eastern Asian, Eskimo-Aleutian, and Native American). Occasionally classification is difficult because of the presence of a combination of racial features, but comparison with a known is still possible. Somatically, hair can be distinguished as scalp, facial, public, body (trunk), and limb. Body and limb hairs are generally considered unsuitable for comparison purposes.

Collection:

1. If possible, collect the entire item with the hair on it and let the laboratory remove the hairs. If this is not possible, remove hairs from surfaces with clean tweezers. Take care not to crush the hair with tweezers when handling it.

2. Place the hair in a pillbox or a folded piece of clean paper, taking care not to kink or crush the hair.

3. If you use an evidence sweeper (vacuum), remove the material that accumulates in the filter and the filter paper and place it in an evidence bag. Do not use envelopes for packaging filter sweepings or for other very small materials.

4. Seal (making sure there are no holes) and label the container, including your initials, the date, and the exhibit number.

5. Collect a comparison sample, if needed (see below).

Hair Comparisons

Traditional forensic hair comparisons have been based on observation of the gross physical characteristics and microscopic structural features exhibited by the questioned and known hair samples. Microscopic hair comparisons do not provide a basis for absolute personal identification. If questioned hair is found to exhibit the same gross and microscopic physical characteristics as are present in the known hair sample, then the source of the known sample could be the source of the questioned hair. Occasionally, similarities and differences are noted on comparison of questioned and known hairs such that the known source can be neither associated with nor eliminated as the source of the questioned hair. Serological and DNA techniques currently applicable to the examination of hairs typically require the presence of adequate root and follicular tissue and are thus effectively limited to the analysis of forcibly removed hairs.

Obtaining Known Hair Samples

The sample must include hairs representative of the entire range of variation present. The following is the recommended procedure for the collection of a known human scalp hair sample suitable for microscopic comparison purposes.

Since most of the questioned hairs recovered in explosives, arson, and firearms-related cases are found to have been naturally shed rather than forcibly removed, known hairs recovered by combings are most likely to correspond to the questioned strands. Human scalp hair typically grows actively for 1000 days, remains dormant for 100 days, and is shed at the rate of 100 hairs per day (approximate values). The microscopic structural features upon which a comparison is based tend to differ depending on the phase of the hair. Hairs of a similar growth phase will resemble each other most closely.

To take the sample, you will need:

  • Clean, new, fine-toothed comb
  • sharp scissors
  • plastic or rubber gloves
  • plain white bond or photocopier paper
  • paper envelopes

Procedure

1. Thoroughly comb all areas of the person's scalp to recover as many loose and/or easily removed hairs as possible. Place the hairs as they are recovered onto a sheet of plain white paper. Keep combing, tugging gently if necessary, until at least twenty hairs are recovered. Fold the sheet of white paper several times so as to thoroughly enclose the collected hairs. Place the folded paper sheet into a paper envelope labeled COMBINGS.

2. Using sharp and preferably small-bladed scissors, cut a few hairs at a time as close to the scalp as possible in a variety of locations about the person's head. Attempt to sample each region of varying length, growth density, color, or cosmetic treatment observed. Place the hairs as they are recovered onto a sheet of plain white paper; it is not necessary to separate hairs cut from different scalp regions. Fold the sheet of white paper several times so as to thoroughly enclose the collected hairs. Place the folded paper sheet into a paper envelope labeled CUTTINGS.

3. Grasping a single hair at a time as close to the scalp as possible, hand pluck at least a dozen individual hairs from the person's head. Avoid regions of obvious hair thinning/hair loss. Place the hairs as they are plucked onto a sheet of plain white paper. Fold the sheet of white paper several times so as to thoroughly enclose the collected hairs. Place the folded paper sheet into a paper envelope labeled PLUCKINGS.

4. The known scalp hair samples thus collected consists of combings, cuttings, and pluckings.

Comments

Plastic or rubber gloves are recommended to protect the hands and improve the grasp (especially during plucking). Unless the hair is too short to handle directly, the use of tweezers for plucking is not recommended, as the recovered hairs are more likely to be crushed or torn off above the root than if plucked by hand.

By including full-length cuttings in the known hair sample, the investigator is able to ensure that each region of varying length, growth density, color, and observable cosmetic treatment is adequately sampled; and that the hairs obtained by cutting were indeed growing from the person's scalp.

By including pluckings in the known hair sample, the investigator is able to provide complete hairs with roots and adhering follicular tissue; and the further obtain hairs that were irrefutably growing from the person's scalp.

For advice regarding the collection of animal hairs or of human hairs other than from the scalp, please telephone the laboratory. The chemist familiar with the questioned hairs recovered in a specific investigation will be able to suggest what known samples are needed for comparison.


Impressions

Impressions made by footprints, tires, and tools can easily be destroyed during a preliminary crime scene search. To prevent inadvertent loss of such evidence, the scene should be properly secured and impressions sought out early. Because impressions can be easily destroyed, they should be photographed immediately upon discovery.

Collection of Footprints and Tire Prints

1. Photograph each print. Place a ruler next to the print. Take the photograph by holding the camera directly over the impression while illuminating the impression by holding a detached flash or strobe light, low and to the side of the impression.

2. Prepare plaster or other casting material and make it a plaster impression of each print. Make sure you have sufficient practice in casting because the cast will destroy the impression when removed and you will not get a second chance. The cast should be reinforced with plastic coffee stirrers, pieces of coat hanger wire, etc.

3. When dry, scratch your initials, date, and exhibit number into the back of the cast.

4. Also scratch or mark a directional arrow pointing North on the back of the cast.

5. Wrap each cast separately using corrugated paper and place in a well-padded box or container. Do not remove dirt adhering to the cast.

6. Seal and label the container, including your initials, the date, and the exhibit number.

7. Collect a comparison, if possible. Collect shoes or other footwear worn by suspects and send them to the laboratory properly packaged in appropriate sealed and labeled containers. Preserve any soil particles which are attached to this footwear according to the Soil section. Make casts of any tires used by suspects for comparison with plaster casts. Also send soil particles found on the tires according to the collection method in the Soil section.

Collection of Toolmarks

1. Whenever possible, preserve toolmarks as you find them and submit the intact object bearing the tool marks to the laboratory properly packaged in appropriate sealed and labeled containers.

2. If it is not possible to submit the intact object bearing the toolmarks, remove that portion or section of the object (i.e., door jambs, car fender, doorknob) and submit properly packaged in appropriate sealed and labeled containers. Before you remove any portion of an item, photograph the entire item. Submit this photograph with the intact object being forwarded to the lab for examination.

3. Collect a comparison sample, if possible. Collect any tools that may have been used by suspects and send to the laboratory, properly packaged in appropriate sealed and labeled containers.


Ink

Chemical analysis of ink can assist the document examiner in characterizing, dating, and/or comparing document evidence bearing questioned ink entries, signatures, or images. Ink may also be encountered in unconventional applications (e.g., permanent marker used to blacken an altered firearm), and the characterization and comparison of such questioned ink may provide an association with known materials or writing instruments recovered from a suspect.

In general, inked images can be characterized as having been prepared using writing inks intended primarily for use on paper (ballpoint; nonballpoint); markers intended for use on a variety of substrates (permanent; dry-erase; paint); or printing inks. Laboratory analysis of a questioned writing ink may enable identification of its manufacturer and/or specific formula; such information may be of investigative value or may enable dating of the document which bears the questioned ink.

Physical and chemical examinations can be undertaken to compare questioned inked images with each other and/or with recovered ink materials or writing instruments. The determination that two inks are of the same composition demonstrates that they could have a common origin. Except in extremely rare cases where a pen nib or tip is so flawed as to leave an individualizing "toolmark" on application of its ink to the substrate, it is not possible to match a questioned ink with a specific writing instrument.

Any comparisons of ink based upon physical examination and chemical analyses should be undertaken PRIOR TO latent fingerprint examinations. For advice regarding the collection and submission of evidence for specific types of ink-related examinations, telephone the ATF National Laboratory or your state or local laboratory.


Liquids and Thick Liquid Substances

Handle liquids carefully to prevent evaporation and contamination.

Collection of Liquids

1. Be aware that liquid containers may contain latent fingerprints and should be handled accordingly. Follow the steps in the Fingerprints section.

2. Non-corrosive liquids in a container can be poured into unused metal cans, sealed tightly and transported and stored upright.

3. Glass or plastic containers with appropriate tops should be used for corrosive liquids found in a container.

4. If the liquid has been spilled on a non-porous surface, spoon or scrape as much as possible into a tightly capped glass vial or bottle. Even if only a few drops can be obtained, a meaningful analysis can be performed.

5. If the liquid has been spilled on a porous or absorbent surface such as carpeting or soil, remove the item as described in the appropriate section and place the wet portion of the material into a tightly capped glass or metal container.

6. Seal and label the container, including your initials, the date, and the exhibit number.

7. Bottles should be carefully packed upright in polyurethane chips or similar material to prevent breakage. Label the boxes FRAGILE.

8. Collect a comparison sample, if possible.

If a liquid is suspected of being hazardous, DO NOT SHIP VIA MAIL. Check with courier and parcel delivery services for shipping instructions, or hand carry to the lab.

Collection of Thick (Viscous) Substances

1. Be aware that viscous substance containers may contain latent fingerprints and should be handled accordingly. Follow the steps in the Fingerprints section.

2. If the substance appears to be grease, do the following:

--for small amounts, wipe up the substance with a cotton swab and place in a labeled plastic bag and seal.

--for large amounts, transfer substance to a sealable plastic container using cotton swabs or a plastic spoon.

3. If the substance appears to be oil or glue, do the following:

--if possible, transfer by pouring into a clean, unused metal can with a tight-fitting lid.

--if the material is in a tight-fitting container which is not larger than one pint, submit it in the original container.

--if the substance is too viscous for pouring, transfer it to a container using a clean plastic spoon or other instrument.

4. Seal and label the container, including your initials, the date, and the exhibit number.

5. Collect a comparison sample, if possible.


Metals

Metal can include tools like ice picks or jimmies or crowbars, or pieces of metal and metal filings found after tool use. Metal can show a wide range of identifiable characteristics.

Metal is of particular evidentiary value as a substrate for toolmarks imparted during original manufacture and/or acquired thereafter. The comparison and association of metal objects includes consideration not only of their physical construction, markings, and chemical composition as manufactured, but also of any "after market" toolmarks imparted by a suspect. In the absence of toolmarks or other physical construction/modification features, questioned and known metals may be associated on the basis of corresponding chemical composition and microstructural characteristics.

Collection of Filings

1. Collect filings caused by sawing, drilling, or filing by carefully lifting or scraping them with a non-metallic instrument into a plastic bag.

2. Seal and label the bag, including your initials, the date, and the exhibit number.

Collection of Unembedded Fragments

1. Collect with a non-metal instrument and place in plastic bags or other suitable non-metallic containers.

2. Seal and label the bag, including your initials, the date, and the exhibit number.

3. Package the items, using padding that will prevent any damage to identifying characteristics or to the area along a fracture plane.

Collection of Embedded Fragments

1. Collect the item that the fragments are embedded in and allow the laboratory to remove them during the examination process. Package as much of the solid matter holding the fragments as practicable, taking care if you have to remove a chunk from a larger object (cut well away from the fragments).

2. Use a suitably sized container to hold the item.

3. Seal and label the container, including your initials, the date, and the exhibit number.

4. Collect a comparison sample, if possible.

Collection of Large Sections

1. As always, photograph the visible marks on objects that are too bulky to remove. Include a ruler in the photographs.

2. Preserve visible marks by casting in a silicone rubber compound.

3. Package and label the casting, including your initials, the date, and the exhibit number.

4. Collect a comparison sample, if possible.

Comparisons may be tools you suspect may have left the fragments or filings or other pieces of metal found, for example, on a suspect's clothes.


Paint

Paint can be found as fragments or chips (i.e., sweepings from the floor), transferred smears (such as from painted wood to a saw blade), as applied surface coatings (a spray-painted gasoline can), or in liquid form.

On laboratory examination, a questioned paint sample can be characterized as to its color, general type, and likely origin (automotive or household). In the case of automotive topcoat fragments or smears, it may be possible to suggest the make and model of the vehicle of origin.

Under infrequent circumstances, a recovered questioned paint sample can be physically matched (on the basis of fracture edges or surface striations/scratches) to the known source from which it originated. More commonly, questioned and known paint samples are associated on the basis of color, composition, and mode of application; where multiple layers are present, their number, color, composition, relative thickness, and sequence can provide an increasingly stronger association with each positive point of comparison.

If possible, submit liquid paint in its original container. Uncontained liquid paint samples should be collected into vapor-tight vials or cans.

Collection of Chips and Smears

1. If found on an object of collectible size (clothing, carpet, bedding), collect the object into an appropriate container such as a paper or plastic bag, making sure the area containing the paint is protected from any abrasion or destruction by covering these areas with plastic or brown paper.

2. If chips are found loose, pick them up with tweezers or by scooping on a piece of paper. Place chips in a leakproof container such as a pillbox, seamless can, or vial. Do not stick paint particles onto adhesive tape. Do not pack chips in cotton. Both of these retention methods impede laboratory recovery and examination of particulate evidence.

3. If chips or smears are found on a non-portable object, chip the paint fragments off the substrate using a clean knife or other instrument, keeping its entire layer structure intact. Remove the entire sample, getting down to bare metal or wood if necessary. Do not merely scrape the surface of the paint or scratch in a way that reduces the sample to powder. Instead, pry away full-depth pieces. Try to dislodge fragments onto a clean piece of paper by tapping the object. Transfer the fragments from the paper into a pillbox, a glass vial, or other container which can be tightly capped. Do not pack paint fragments in cotton. Do not allow paint to touch adhesive.

4. If the smear is wet, let the paint dry completely before placing the smeared item in a protective container as in step 1. If the smear is wet on an object of non-collectable size, allow to dry and then follow step 3.

5. Seal and label the container, including your initials, the date, and the exhibit number.

6. Collect a comparison sample, if possible, from the suspected source of the paint.


Plastics, Adhesives, Asphalt, Tar, Waxes, Grease, and Oils

Plastic wrapping film, bags, jugs, and other device or accelerant containers; wire insulation; or rubber foam are some examples of polymeric materials that can be categorized by the laboratory. Comparison of grain and/or pigment patterns, perforations, and surface scratches imparted during manufacture can demonstrate the common sequential origin of questioned and known plastic garbage-type (pigmented) bags. In the absence of such individualizing features, plastic films and bags may be compared on the basis of color, composition, construction, thickness, and inclusions.

In addition, adhesives and sealants are frequently employed in the construction of delay devices or incendiary devices. Roofing or paving material, waxes, oils and lubricants can be used as accelerants and found as trace evidence on items recovered from a scene or suspect. These substances may be characterized as to their general type and likely source(s), and can be compared with known materials on the basis of color, composition, method of application, and fillers/inclusions.

In addition, plastic can be an excellent substrate for toolmarks, such as a container cut to hold accelerant, that can be matched to a known tool.

Evidence of this type should be collected according to its composition: liquid or viscous.


Questioned Documents and Paper/Cardboard

Documents and paper contain a wide variety of identifiable characteristics. It may be advisable to contact the document examiner prior to collecting known samples so that the most complete and accurate material is available for comparison.

Paper/Cardboard Evidence

Paper and cardboard materials are encountered as the substrates of document evidence, such as wrapping paper used to conceal a destructive device, paper towel trailers used to spread an accelerated fire, and paper matches. Watermarks in writing or typing paper and printed or embossed designs on paper tissues and toweling may enable manufacturer identification of these products. Physical matching of the torn or cut edges of paper or cardboard can demonstrate an association between questioned and known materials to the exclusion of all other sources. In the absence of a physical match, comparison of physical dimensions; color, dyes, printed images; inclusions; fiber content, fillers, coatings; perforations and other construction features (e.g., angle and direction of twist in a cardboard tube wrap) can enable the general association of questioned and known paper or cardboard materials on the basis of these class characteristics. Such physical and chemical comparisons of paper and cardboard substrates should be undertaken PRIOR TO any latent fingerprint examinations of the evidence. Collect as below for documents.

Collection of Charred Documents

1. Search area of charred documents carefully; a stray breeze could destroy evidence.

2. Be sure to photograph the charred paper remnants to record their location and position. Photograph and record any decipherable writings that may be apparent on flat sheets.

3. Lift the charred documents by sliding a cardboard sheet, piece of glass, or metal plate under the evidence, then slide the material into a rigid container lined with cotton batting. Use tweezers to pick up small fragments.

4. Charred documents found in containers such as wastebaskets or safety deposit boxes should be left in the receptacle where found and the entire container submitted.

5. Seal and label the container, including your initials, the date, and the exhibit number. Mark FRAGILE.

Collection of Intact Documents

1. If fluid- or blood-soaked, allow to air dry first.

2. Whenever possible, submit the original document rather than a photograph, photostat, or other type of copy. Do not use staples or pins on the documents. Do not fold the documents.

3. Place the document in a protective covering such as an envelope or plastic document sleeve.

5. Seal and label the container, including your initials, the date, and the exhibit number.

6. Collect a comparison standard, if possible, as per below.

Comparison Standard--Questioned Documents

There are two kinds of known documents:

Nonrequest or collected known documents are those which are obtained from normal course of business sources (employment records, banking records, institutional records, etc.) and which can be presented to a court by a record custodian as having been prepared by the suspect. In searching for nonrequest known documents the investigator should confine the material collected to that which is comparable to the questioned. Only known script handwriting can be used in a comparison of questioned script writing, only known handprinting can be used in a comparison of questioned handprinting, only paper of similar color need be obtained for a comparison with a questioned paper.

Request or dictated known documents are those produced specifically for the investigation (e.g., handwriting produced by the suspect as dictated by an investigator, typewriting taken from a suspect machine by an investigator, paper or ink samples taken from the suspect's residence, etc.) Record the origin of all known documents.


Soil

Soil composition varies considerably over short distances of the earth's surface and depth. While a questioned soil sample cannot be identified as having originated from one source to the exclusion of all others, forensic soil examinations can provide compelling investigative leads because the material is so variable. The presence in soil of manufactured materials such as concrete, plaster, abrasives, and/or glass may suggest a specific industrial location of origin or strengthen association of samples. Soil and minerals may show where items and persons have been, even at the crime scene area. Soil samples may be layered. Try not to disturb the layering effect when collecting samples.

Collection

1. At the crime scene, determine the areas where transfer of soil to the suspect or her/his belongings is likely: footwear or tire impressions; muddy or excavated areas.

2. Collect several small samples from the immediate area(s) of interest; dig no deeper than shoes or tires would depress the soil. Use a spoon, knife, or other clean suitable instrument. Package the soil samples individually in small seamless cans, leakproof pillboxes, or plastic film canisters, in order to preserve intact any cohesive lumps. Cushion the sample using facial tissue or cotton padding to prevent crumbling. Do not use paper envelopes or glass containers to package soil samples.

3. Collect additional small shallow samples in at least four different directions and up to 100 yards away from the immediate area(s) of interest, to enable the laboratory to demonstrate the soil variation present in the overall location and to strengthen any observed association between the specific crime scene area(s) and any subsequently recovered questioned samples. Use a spoon, knife, or other clean suitable instrument.

4. To prevent putrefaction or molding of recovered soil samples (either known or questioned), allow them to air-dry prior to submission to the laboratory.

5. In collecting questioned soil samples from inside of vehicles or buildings, attempt to keep existing lumps intact by carefully removing with tweezers or a spoon and packaging them individually in small seamless cans, pillboxes, or plastic film canisters. Soil present on the floor mats of a car, for example, is likely to have originated from multiple sources; mass collection of such material by vacuuming or otherwise crushing and mixing the lumps by improper packaging, will render the sample useless for comparison purposes. Cushion the sample using facial tissue or cotton padding to prevent crumbling.

6. Similarly, attempt to collect questioned soil samples from vehicle tires in discrete lumps, packaged individually, to ensure as much as possible that each sample collected represents a single source. If in doubt, submit the tire to the laboratory for sample recovery.

7. Avoid packaging a small clump of soil into a large container in which it may rattle about and break apart on transit. The laboratory needs to be able to examine intact lumps of soil, not individual particles.

8. Soil which likely has been deposited in layers, such as soil accretions present underneath vehicle fenders, should be sampled in such a way as to preserve the layers intact. Chip or cut away samples bearing the full thickness of such layered soil deposits; package individually in small cans or pillboxes, using facial tissue or cotton padding to prevent crumbling and mixing of the recovered samples on transport.

9. Shoes, clothing, tools, and other removable or portable objets bearing questioned soil deposits should be packaged individually and submitted to the laboratory without attempting to remove the soil in the field.

10. Seal and label the container, including your initials, the date, and the exhibit number.

Other types of geological/mineralogical evidence include laboratory characterization of rocks, minerals, abrasives, building materials, and safe insulations.

Collection of Dry Soil

1. Collect as much soil as possible, preferably more than half a pound.

2. Place dry soil in a metal can. Do not use envelopes or glass containers for dry soil.

3. Seal and label the container, including your initials, the date, and the exhibit number.

4. Collect a comparison sample, if possible.


Tape

Tapes of various sorts are frequently used in the construction and/or deployment of destructive devices, and in the alteration of firearms (e.g., sawed-off stock). Black plastic electrical tape, silver or gray colored duct tape, masking tapes, black friction tape, and medical ("adhesive") tapes are the varieties most often encountered in explosives, arson, and firearms-related investigations.

A torn or cut end of tape recovered from a crime scene or device may be found to physically match the end of a partial roll recovered from a suspect. In the absence of a known tape sample, questioned tape may be characterized as to its type and possible manufacturer. In the absence of a physical match, questioned and known tapes may be associated on the basis of common physical construction, color, and chemical composition.

Often, the tape employed to construct a device or alter a firearm is applied in overlying layers; trace evidence trapped and preserved between these layers may be reasonably regarded as having originated from the environment of construction. Even post-blast, sections of these overlaid tape layers do survive and may bear identifiable fingerprints, hairs, fibers or other trace evidence of associative value.

In cases where a tape-wrapped device such as a pipe bomb is recovered intact and it is deemed necessary by the bomb technician to remove the tape as an element of the render-safe procedures, it is recommended that the tape layers be cut and laid open as a single unit rather than "unwound." The recovered overlaid tape can then be placed as a unit onto a polyester sheet (e.g. document protector) or heavyweight polyethylene bag for submission to the laboratory, where the layers can be removed and examined individually for the presence of fingerprints, glove impressions/fiber transfer, and other trace evidence.


Wood

Wood may occur as large pieces, like a door frame or box, in small pieces like wooden matches, or as small fragments like splinters or sawdust. Laboratory characterization of questioned wood generally includes determination of its genus or species and suggestion of possible sources based upon its observable physical features and condition. Characterization of the manufactured structure of questioned pieces of wood may provide further investigative leads; for example, certain plywood and veneer constructions have fairly specific intended applications, thereby reducing the number of possible sources of such materials within a given geographic area.

If the available pieces are of sufficient size, questioned and known wood sections may be associated on the basis of a physical match of fractured edges or a grain pattern match across cut sides or ends. In the absence of a fracture or grain pattern match, wood evidence may be associated on the basis of common species; physical dimensions and construction features; planing or other manufacturing toolmarks; and chemical surface treatments, coatings, or adhesives.

Wood evidence should be collected as per glass evidence. Large pieces should be carefully and appropriately packed given the nature of the item. Take care to use padding to preserve any fracture areas where comparison is desired.


Recovery of Evidence from Victims

abstracted from a document contributed by Dr. John D. DeHaan, Forensic Scientist, California Dept. of Justice, Criminalistics Institute

All victims, dead or alive, may be a source of evidence. These victims may not be at the scene when you arrive, they may have been transferred to the hospital or morgue. To recover this victim-borne evidence:

1. When you arrive on scene, you should immediately secure information on any injuries and fatalities and the location of those victims. Pursue these victims as soon as possible for any information you can get from interviewing a live victim, as well as securing potential trace evidence from the person, alive or deceased.

2. Do not disturb any bodies at the scene. Secure the location of the body so it can remain undisturbed and call the coroner as per the protocol in the interFIRE VR Tutorial section entitled Handling Injuries and Fatalities. The location, position, and condition of the body may tell you how the fire spread or started.

3. For all victims, secure the clothing and shoes, as they may contain trace evidence such as accelerants, hair, or fiber.

4. If an explosive event took place in addition to the fire, whether by accident as in a propane tank explosion or through intent as in a pipe bomb, additional evidence may be embedded in the tissue of the victim. Explosion victims should be x-rayed for shrapnel evidence, and may need to be autopsied or operated on with an explosives expert present who can identify items removed from the body as potential evidence.

5. Be aware that bodies pose health risks in the collection of evidence, include blood-borne pathogens. Collection of evidence at the scene should be done by specialized personnel, like the coroner or a forensics technician. You should coordinate with these individuals in the processing of the body for evidence. You will want to coordinate the photographing, diagramming, collection of clothes, and collection of other evidence. Remember that blood-soaked items must be dried before packaging. This can be done on butcher paper at the scene. Ensure that proper procedures for blood evidence collection are followed (see Body Fluids for more detail).

6. Fragments from an explosive event should be collected by the specialist and then transferred to you. Remember blood-soaked fragments may contain blood-borne pathogens. After any blood evidence is collected from them, these fragments may be lightly rinsed in slowly running distilled water to cut down on blood-borne pathogens from dried blood and tissue attached to the fragment. Any rinsing of large accumulations of blood and tissue should be done very carefully so accelerant or explosive residue is not lost. Only items with large accumulations of blood and tissue should be rinsed. Allow to air-dry before packaging. Final packaging can be in plastic or glass containers, plastic or paper bags, or boxes. Mark evidence with a biohazard label before sending to lab. The location of each piece of debris should be recorded.

interFIRE VR Tutorial "Collect and Preserve Evidence"

 
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