Investigations | Section 5.3


Fundamentals of Criminal Investigations

Adam J. McKee, Ph.D.


DRAFT - Do Not Distribute

This content is released as a draft version for comment by the scholarly community.  Please do not distribute as is.    


Section 5.3: Packaging Trace Evidence

Trace Evidence deals with the collection of all forms of matter, natural or manufactured, usually very tiny materials, but may also be larger forms of matter. Examples are gas from a container (bag or metal cylinder), hair, pollen, stains (non-biological), volatile liquids, fibers, paint, glass and soil. Trace evidence can be easily destroyed, contaminated, or transferred, so take precautions when approaching the scene. Since trace evidence items are often difficult to see without the aid of magnification, the prudent course of action is to collect items of evidence that may contain trace evidence.

Care should be used when collecting weapons, as improper handling and packaging can compromise the trace evidence. Careful photography, documentation, and sketching are critical for the optimal use and interpretation/reconstruction of trace evidence. Always package items to prevent damage or alteration of the evidence: use packaging that corresponds to the size and type of the item and evidence. Always collect sufficient amounts of the trace evidence when possible.

Do not package evidence if it is wet or damp. Do not package exemplar, standard/reference, or control samples with evidence. Package separately. Use of a bright or alternative light source may help in locating trace evidence. Standard, reference, and control samples should be collected for laboratory comparison, examination, or elimination purposes. Collect enough for multiple analyses. Always wear powder-free gloves while collecting trace evidence to avoid contamination. Change gloves as often as needed to minimize contamination.

Documentation and Marking

Do not package evidence stained with bodily fluids or other liquids in plastic bags. Avoid altering the trace evidence in any way, other than is necessary for evidence collection (e.g., scraping paint from a metal surface). When possible, when storing evidence, use a freezer/refrigerator that is dedicated to evidence storage to guard against potential biohazard contamination or explosion hazards.

Do not cough, sneeze, talk, or scratch yourself over any sample being collected or to be collected. When using tweezers/forceps, use only sufficient pinching force to collect item to prevent altering or damaging the trace evidence. Keep adhesive tape to be used in lifting evidence in a plastic bag until just before use to prevent contamination of the edges/side of the tape roll. Put unused portion of tape roll back into the plastic bag when finished with tape lifting. Do not place trace evidence directly into manila envelopes (of any size), paper envelopes, or paper bags without placing the evidence into a smaller, leak-proof container such as a glassine bindle, canister, Teflon-lined screw cap glass vial (or bottle/jar as size dictates), or other container. Keep clear acetate sheet protectors free from contamination by storing in an appropriate size manila envelope or plastic resealable bag. Careful photography, documentation, and sketching are critical for the optimal use and interpretation/reconstruction of the evidence.

To reduce breakage and loss of evidence, secure glass containers (e.g., vials, bottles, jars) in cushioned metal friction lid cans with lids. Cushioning material may be balled-up paper towels. Using a swab to collect a trace evidence sample—whether liquid, powder, gel, or other form of matter, evidential or control—is a last resort.

Ensure that the portion of the object with the stain or other trace evidence has been photographed and documented in notes and sketches. When photographing the object: Include a scale and an identification label. Photograph with and without scale. Take one or more location photographs that show where the object was found in relation to other objects in the crime scene. Show the relationship of the object to other evidence in the photograph.

Label a container for the evidence object with your initials and identification number, the date and time, evidence number, location, and evidence description.

Evidence number: Each piece of evidence must have a unique number. This number should correspond to the placard or identification label next to the evidence and the evidence log as appropriate.

Evidence description: The evidence description includes: Type of evidence (paint, plant stem, glass, etc.) Original location of the trace-evidence-containing object Location of the trace evidence on the object (as appropriate) When describing non-DNA-related stains, use the word “apparent” or the phrase “of unknown origin” when the source of the stain is not scientifically identified; e.g., “Pillow containing a brown stain of unknown origin found on the lower bed sheet on the bed.” Label the container just before collecting the object, and seal the container immediately after collection. These actions help to protect the integrity of the trace evidence and the chain of custody.

Wet Trace Evidence

If the item is wet, determine if the liquid is significant or relevant to the case (for instance, acid splashed on a victim). You may not wish to dry the item if the liquid is relevant to the case. If the liquid is not relevant, place item on a clean piece of paper in a secure location used for evidence drying, such as a drying rack, until it is dry. If you have access to a drying rack, dry the item in it. Place a clean piece of paper below the evidence to be dried in the drying rack. Lay the item on or hang it above the paper.

If you do not have a drying rack:

  • Lay a clean piece of paper on a clean flat surface (e.g., table top) in a secure location where the item will not be disturbed and contamination or loss of the trace evidence due to drafts created by people walking by will be minimized.
  • Carefully place the item on or hang it over the paper. If possible, gently fold the paper over the object to cover it from airborne particles (such as hair or fibers) that might land on it.
  • Allow the item to dry naturally. Never expose it to heat or significant drafts, such as from a blow dryer. Avoid exposing the sample to direct sunlight.

Do not place two items in the same container for drying purposes. If the liquid is relevant to the case, determine if the liquid is related to a fire or explosion and in or on an object (e.g., ignitable liquid in carpet).  If so, contact fire investigator or bomb technician or forensic fire debris or explosives analyst as appropriate.

If the liquid is involved in injury or damage to another person or property and on an object, it should be collected as evidence.  Proper collection depends on the size of the sample. If the sample is small, secure it in appropriate size glass container with a Teflon-lined screw cap lid or other airtight, non-reactive lid.  If the sample is large, document location of wet area by photography, notes, and sketches, then cut or remove the wet area and treat as if small sample.

If the liquid is soaking the object or there are drops of liquid on the surface (non-porous surface), using gloved hands, attempt to squeeze liquid drops into glass container or use swab to collect drops and treat as small sample.  If the liquid is forming a large drop or pool of liquid, transfer the liquid using glass Pasteur pipette or plastic transfer pipette into appropriate size glass vial. Consider appropriate hazardous labeling.

When the object has dried, carefully pick up and fold the paper on or over the object that has dried. Contain any trace evidence that may have fallen on the paper. Label the folded paper, indicating the evidence number of the item that was dried (e.g., “This paper was used below evidence #36 while it was drying”).   If possible, repackage the object using the original paper and container.

If the original container cannot be reused, save all original packaging as evidence if it is not used for repackaging.  Put the labeled, original packaging into a new container with the evidence it was used to collect. Label the container indicating the evidence number of the item (e.g., “Original packaging for evidence #36”).  When possible, place glass vials, bottles, and jars into a cushioned metal friction lid container to reduce breakage. To reduce breakage and loss of evidence, secure glass containers (e.g., vials, bottles, jars) in cushioned metal friction lid cans with lids. Cushioning material may be balled-up paper towels.

Collecting Control Samples

A control sample is one that the collector knows, that does not appear to have evidence present. It represents the matrix material on which the evidence rests, for instance a piece of wallboard or carpeting. A comparison sample may have evidence present without the collector’s knowledge (e.g., fire debris), but represents the matrix material on which the evidence rests or is made of the same matrix material as the evidence (e.g., glass fragments collected from a broken window). It will be compared to the evidential sample. These will be referred to as “control” samples.

Label a second container for the control sample with your initials and identification number, the date and time, evidence number, location of the control in relation to the original sample, and a description of the control sample. Clearly identify this sample as a control (or comparison) sample (e.g., write the words “Control Sample” or “Comparison Sample” in bold print on the container).

Control sample number: Each piece of evidence, including the control sample, must have a unique number. A letter or number may be appended to the original evidence number to denote the control sample (e.g., if the original evidence number was #32, the control sample could be #32A or #32.1.)

Control sample description: Include the type of sample or matrix material (e.g., wallboard), location of the material, and the location of the sample in relation to the evidence sample.  

Collect a control sample: Using the appropriate tool, cut out, collect, or remove a portion of the same matrix material on which the evidence sample rests or was part of the evidence sample (e.g., paint smear evidence on paint). Locate an area of the same material from which the original trace evidence sample was taken, but without evidence being present (e.g., undamaged area of paint).

Cut out, collect, or scrape the control or comparison sample using, as appropriate, a scalpel, utility knife, wallboard saw, carpet knife, single edge razor blade, or scissors. (Whenever possible, use a clean blade; never use a blade that was used to cut an evidential or other control sample without changing or thoroughly cleaning.)

If multiple layers (such as carpet and carpet pad or multi-layer paint) of material were observed or collected in the original sample, collect all of the multiple layers for the control or comparison sample. A liquid sample should be collected using a glass or plastic transfer pipette and placed into a glass Teflon-lined screw-cap vial or bottle of the smallest permitted size for the sample. Using a swab to collect a liquid trace evidence sample (evidential or control) is a last resort. Put the swab into an appropriate size screw-cap vial or other airtight container.

Removing an Entire Object

Photograph and document the object with the apparent trace evidence. Whenever appropriate, wrap the entire object in clean (butcher) paper or in a brown paper bag.  Only wrap an object when doing so will not disturb the position of a stain or other trace evidence (glass fragment, metal fragment, paint smear, etc.). Objects should be wrapped in clean paper when the location or pattern of the stain or other trace evidence is significant (such as a spatter pattern) or the object is saturated and liquid will leak through the container if not wrapped. Position the paper to keep the trace evidence intact in its original form. Avoid transferring any of the trace evidence to another portion of the object. Place the wrapped object into the brown paper bag or other labeled container.

If an object is too large to be packaged in a container, protect the stain or trace evidence area(s) with clean paper during transport. Close the container and seal the entire opening with evidence tape. Write your initials, the identification number, and the date and time across the evidence tape seal. Ensure that any small openings in the package are also sealed. Place initials over these seals.

If an object is too large to be packaged in a container, protect the relevant area(s) with clean paper during transport. Repackage the object using the original packaging, if possible, and reseal. Store the object in the sealed container. Place the container in a secure, dry storage area. Never expose the container to extreme heat, such as from a heater vent. Avoid exposing the container to direct sunlight.

Cut From a Non-portable Object

Label a container for the object to be collected with your initials and identification number, the date and time, evidence number, location, and evidence description. Photograph, sketch, and take notes on the object with the trace evidence or stain. Collect a larger area than where the trace evidence is observed, especially if the shape or pattern of the trace evidence or stain is significant (e.g., paint spray, broken glass pane, etc.).

If possible, cut out the entire area using a scalpel, single-edge razor blade, utility knife, carpet knife, drywall saw, scissors or other tool as needed to remove section. If the trace evidence has been absorbed into multiple layers (such as carpet and carpet pad), collect a cut-out from each layer. If the entire stained or evidence area is too large to collect as one piece, using the appropriate tool, cut out a smaller section of the area and label to re-assemble the sections later if needed.

On the side of the cut-out opposite the side with a stain or trace evidence, mark the orientation of the cut-out to north when collected. Be careful not to dislodge trace evidence while marking. If the item is “wet”, determine if the liquid is water, a biological fluid, volatile, or hydrocarbon.

  • If water or biological fluid, place it on or over a clean piece of paper and allow it to dry before packaging.
  • If the liquid is volatile, acidic, caustic, or a hydrocarbon, the liquid itself may be significant evidence and must be packaged in an airtight container to prevent evaporation. Contact a fire investigator, fire debris analyst, or bomb technician for instructions.

Whenever appropriate, wrap the cut object in clean paper, glassine bindle, or place in appropriate size glass or plastic container or metal friction lid can. Close and seal the labeled container after having placed the object into it. Write your initials and identification number and the date and time across the evidence tape seal. If an object is too large to be packaged in a container, protect the area(s) with clean paper during transport.

Collect a control sample: Using the appropriate tool, cut out or remove a portion of the same matrix material on which the evidence sample rested or was part of the evidence sample (e.g., locate an area of the same material from which the original trace evidence sample was taken but without evidence being present such as an undamaged area of paint). Cut out the control or comparison sample using, as appropriate, a scalpel, utility knife, wallboard saw, carpet knife, single-edge razor blade, or scissors. (Use a clean blade; never use a blade that was used to cut an evidential sample on a control sample without a thorough cleaning or replacement.)

If multiple layers of material (such as carpet and carpet pad or multi-layer paint) were observed or collected in the evidential sample, collect all of the multiple layers present for the control or comparison sample. On the opposite side of the evidential side of the original non-control sample, mark the orientation of the cut-out to north when collected.

Whenever appropriate, wrap the control sample in clean paper or other appropriate containment. Place the object into the labeled container. If an object is too large to be packaged in a container, protect the sample with clean paper during transport. Close the container and seal the entire opening with evidence tape. Write your initials and identification number and the date and time across the evidence tape seal.

Scrape From a Non-portable Object

Use scraping when the entire object may not be collectable (e.g., quarter panel of car, etc.) Often scraping is used to collect evidence on non-porous surfaces too large to collect, but may be used to collect evidence on porous surfaces (e.g., stain on car seat, furniture fabric, canvas, etc.) Paint transfer is commonly located on the object on the impacted surface. Collect the clothing and shoes of people who have been in the area of the painted surface at the time of and since the impact.

Collect paint control-comparison samples, when the entire item cannot be removed, using the scrape method. Always use clean and/or fresh, disposable scraping tools. Change blades frequently when applicable. Always change gloves and use thoroughly cleaned tools when collecting each new sample (between every evidential or control sample.) The stain or marking should be dry for scraping.

Do not use a commercially manufactured envelope of any kind as they have gaps that permit leakage. If a commercial envelope must be used, seal around all edges of the envelope with tape. Label a container for the object to be collected with your initials and identification number, the date and time, evidence number, location, and evidence description. Photograph, sketch, and take notes on the object with the trace evidence or stain.

Collect as much of the evidence area as possible using a scalpel, single-edge razor blade, utility knife, or other tool as needed to remove section. On vertical surfaces, place or tape a self-made envelope or glassine bindle below the area to be scraped before scraping to capture all of the scraping. By scraping the sample, typically all shape or pattern of the trace evidence or stain is lost.

Documenting and Marking Scrapes

Label a container for the evidence-scraped object with your initials and identification number, the date and time, evidence number, location, and evidence description. Use a druggist fold to create a glassine paper bindle or self-made envelope. Evidence number: Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence and the evidence log as appropriate.

The evidence description should include the:

  • Type of scrape evidence (paint, apparent vomit, etc.)
  • Original location of the object containing the trace evidence
  • Location of the trace evidence on the object (as appropriate)

Label an appropriate container just before collecting the scraping, and seal the container immediately after collection. Place a large sheet of clean paper beneath the area that you will scrape. The paper is used to contain any debris that breaks loose while you are scraping. Avoid standing on the paper while you scrape. Place or tape a self-made envelope or glassine bindle below the area to be scraped before scraping to capture all of the scraping possible. Do not use a commercially manufactured envelope of any kind as they have gaps that risk leakage.

Scrape off as much of the material as possible and go as deep as possible to obtain all layers. Note: When scraping flakes, attempt to leave the flake as intact as possible as you remove it. When scraping paint, as when found on a car, scrape down deep to the base material, such as the metal of the car. Collect all layers of paint available (all evidence layers and all matrix layers on which evidence rests) in one scrape. This method applies to all trace evidence to be scraped.

If ample evidence is present, attempt to collect a sample that is at least the size of a quarter when scraping material that is not a flake. Otherwise, scrape and collect all of the evidence present. Scrape the material directly into a paper bindle or self-made envelope. A bindle or self-made envelope is preferred for collection to be able to recover as much of the evidence from inside of it as possible. Close and seal the bindle or envelope to prevent leakage.

Never use staples to seal a bindle containing trace evidence. Place a small section of tape at the point where the top is tucked into the bottom just sufficient to keep the bindle top tucked into the bottom. Do NOT over wrap the bindle or envelope with tape. Place the bindle or self-made envelope into an appropriate size labeled container.

Take necessary precautions to avoid breaking or damaging larger flakes by affixing the bindle or envelope to a piece of cardboard or other rigid material. Secure the bindle or envelope to keep it from moving with minimum amount of transparent tape (not evidence tape or packing/tape lifting tape). Fold the paper that was below the paint when scraped, and place it into a labeled container.

Keep all evidence from the same scrape together using detailed labeling of the containers and evidence tape. Close the container and seal the entire opening with evidence tape. Write your initials and identification number and the date and time across the evidence tape seal.  Consider taking a control sample.

Tape Lifts

A tape lift has the advantage over vacuuming by collecting evidence most recently deposited relative to the crime. Suitable types of tape to use are packing or box-sealing tape with a width of 2.5 inches to 4 inches. Do not use fingerprint lift tape, latent print tape strips or lifters unless as a last resort. While excellent for fingerprints, these often have insufficient adhesive for trace evidence. Do not use masking tape, clothing hair-removal tape, duct tape, or other non-transparent tapes. Do not use paper as a backing for tape adhesive. Use acetate page protectors or clear secondary liners.

Hair is frequently located at a crime scene near a weapon, near the point of impact, and below a deceased person, on clothing worn during the crime. Fiber is frequently located at a crime scene on clothing, carpet, furniture, and bedding. Fiber is usually defined as carpet and clothing filaments. Broken glass is frequently found on clothing, shoes, head hair, skin, tools, and weapons.

Paint is commonly located on the object that impacted the painted surface, the area below/around the painted surface that was impacted, and the clothing and shoes of people who have been in the area of the painted surface at the time of or since the impact. Do not freeze the lift. To collect paint samples when the entire item cannot be removed, use the tweezers collection method first, then the scrape method, then the tape lift method. Always use powder-free clean gloves when handling evidence.

Documenting Tape Lifts

Whenever possible, collect the entire item and submit it to the lab. Collect trace evidence (e.g., hair, fiber, paint, etc.) using tweezers when possible, then use tape lifts. Marking Evidence Evidence number: Each piece of evidence must have a unique identification number. This number should correspond to the placard next to the evidence and the evidence log as appropriate. Evidence labeling: Label the acetate page protector or secondary liner along an edge and a container for the sheet or liner with your initials, identification number, the date and time, evidence number, lift location (e.g., lower, bed sheet, left-front shirt). Label each tape lift with your initials, the date, and identification evidence number. As appropriate (e.g., when collecting a series), add additional specific location information to the tape end.

On the tape, a letter may be appended to the original evidence number to denote the lift. If the original evidence number was #36, for example, the number on the bindle could be #36A or #36.1. If several lifts are from the same evidence item (e.g., shirt) then the same sub-number (e.g., #36A) can be used for all lifts on the same acetate page protector or unique numbers used for each separate lift, according to department preference.

The evidence description should include the:

  • Type of evidence
  • Location of the evidence
  • Description of surface from which lift is taken
  • Brief description of evidence, when appropriate, such as “blue-colored glass” or “apparent smokeless powder”

On the envelope, avoid using adjectives, such as “long” or “blonde”, to describe hair; e.g., “Hair and other items lifted with tape from green area rug lying across the floor two feet east of the back door.” On the bindle, when it is used for debris, refer to the evidence with which the content of the bindle is associated; e.g., “Debris from evidence #36.” Label the container just before collecting a sample, and seal the container immediately after collection.

Tape Lifting Trace Evidence

Tape on a roll or as used in sheets are considered “tape.” Acetate sheets, page protectors, and release liners will be “backing.”

Remove a little longer clear tape from the roll than will be needed to tape lift the intended surface. Fold approximately an inch of tape onto itself on the ends. Place the tape evenly on the surface to be tape lifted. Press repeatedly and firmly along the length of the tape. Peel the tape off of the surface carefully so as to keep evidence from falling off of it.

If the surface pattern is important, place the adhesive side of the tape on the backing. If the pattern is not important, repeatedly place the tape onto new areas of the surface with potential evidence several times, but before the tape loses stickiness. Place the adhesive side of the tape onto the backing.

If lift tape is being used, open the tape lift and remove the protective seal over the sticky part of the lift. If clear tape is being used, remove a piece of tape. While holding the tape over clean paper, close the lift tape or place the piece of clear tape against the sheet of acetate. If lift tape is being used, carefully place the backing over the sticky surface. If clear tape is being used, carefully place the tape on the acetate.

Be sure not to let any evidence fall from the tape lift or clear tape. If the tape lift or clear tape is not sticky enough to securely attach to the backing or acetate, use an additional piece of tape to secure it to the backing. Label the tape with your initials, identification number, the date and time, evidence number, and location as appropriate.

The backing should be labeled along a margin parallel to the direction of the tape with your initials, identification number, the date, evidence number, location and description Packaging Place the tape lift into the labeled envelope. The envelope and tape backing should have identical information on their labels.

Save any debris that fell off of the tape onto the clean paper by folding the paper into a bindle and placing it into an envelope. Take care to fold the paper in such a manner as to contain all debris; using a “druggist fold” to make a bindle is recommended. The container should be labeled in the same manner to match the lift envelope’s label.

If a control or comparison tape lift is made, package separately from the evidence tape lift. Close the container and seal the entire opening with evidence tape. Write your initials, identification number, and the date across the evidence tape seal. Store lifts in a secure, dry storage area until they are submitted.

Collecting With Tweezers

Hair is frequently located at a crime scene near a weapon, near the point of impact, and below a deceased person, on clothing worn during the crime.

Fiber is frequently located at a crime scene on clothing, carpet, furniture, and bedding. Fiber is usually defined as carpet and clothing filaments. Broken glass is frequently found on clothing, shoes, skin, tools, and weapons. Paint is commonly located on the object that impacted the painted surface, the area below/around the painted surface, and the clothing and shoes of people who have been in the area of the painted surface at the time of or since the impact. Always use clean, powder-free gloves when handling evidence.

Do not cough, sneeze, talk, or scratch over any sample being collected or dried. Broken glass is frequently found on clothing, shoes, head hair, skin, tools, and weapons. Paint is commonly located on the object that impacted the painted surface, the area below/around the painted surface that was impacted, and the clothing and shoes of people who have been in the area of the painted surface.

Label a container for the bindle or envelope with your initials, identification number, the date and time, evidence number, location, and evidence description. Label the bindle or envelope with your initials, identification number, evidence number, the date, and evidence description. Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence and the evidence log as appropriate.

Label the bindle and container just before collecting an object, and seal the container immediately after collection. These actions help to protect the integrity of the sample and the chain of custody.

To collect the evidence, gently pick up the evidence using clean tweezers. Use only clean tweezers when collecting a piece of evidence. Grasp the evidence gently and with only sufficient force to securely collect the evidence with the tweezers. When collecting hair, be sure to capture the root of the hair when possible since DNA is contained in the hair root. Continue using the tweezers on all evidence large enough to be collected and place the evidence into the bindle or envelope.

Use and label a different bindle for different apparent types of evidence, different areas of collection (as appropriate), or for other reasons. Close the bindle or envelope to contain the evidence and protect it from contamination or leakage. When closing the bindle, make sure to contain the evidence placed into it. Packaging Place the bindle into an envelope or other container. Close the container and seal the entire opening with evidence tape. Write your initials, identification number, and the date across the evidence tape seal. Store the sealed envelope or container.

Surface Swabs

For most trace evidence, all other methods should be considered superior and therefore, the most appropriate ones attempted first before using a swab to collect evidence. Often the swab collects too little of the evidence or embeds the evidence within the fibers of the swab making removal or recovery difficult for analysis. Reasonable uses for a swab exist, however, such as the recovery of pepper spray from the face of a subject or dye-pack contents from a vehicle interior or hands of a subject.

Label a container for the swab with your initials, identification number, the date and time, evidence number, location, and evidence description. The evidence description should include whether the stain is wet or dry.  When describing stains, use the word “apparent” or the phrase “of unknown origin” when the source of the stain is unidentified; e.g., “Brown stain of unknown origin on bathroom floor.” Label the container just before collecting the swab, and seal the container immediately after collection. These actions help to protect the integrity of the evidence and the chain of custody.

If the stain is dry, moisten the cotton tip of a swab using an appropriate solvent depending on the evidence such as two or three drops of distilled water. Do not saturate the swab with solvent, just enough to “dampen” the swab with solvent.


Key Terms




References and Further Reading

 

Modification History

File Created:  05/02/2019

Last Modified:  05/16/2019

[ Back | Content | Next]


This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

Open Education Resource--Quality Master Source License


 

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.