Fire Scene Evidence Collection Guide

Fabric & Fibers

Large Articles of Fabric or Clothing

Detailed Procedure:

Attempt to collect clothing before it is laundered. Be sure to collect clothing that the suspect and/or victim may have worn while obtaining and transporting ignitable liquids, including socks and shoes. Fabric and clothing can bear trace evidence, so care should be taken to not disturb potential trace evidence when collecting the item. Do not shake out or unnecessarily manipulate the fabric (trace evidence such as glass, hairs, and foreign fibers may be present). Handle the fabric as little as possible.

To collect large articles of fabric or clothing:

  1. Photograph the fabric or clothing in place (if found not on the person) or photograph the person if he/she is wearing the clothes. Take closeups of any stains or other areas of interest.

  2. Wear new, unused, clean latex or nitrile gloves.

  3. Determine what analysis will be requested for the fabric/clothing. This determination affects the collection method and the packaging container. Consult your laboratory for guidance.

  4. Using the appropriate procedure described below, package each article of fabric/clothing separately, unless it is found together (in a laundry bag or duffel bag, for example). If the clothing is on the person, under supervision, have the person remove one article of clothing at a time and package as stated below based on what analysis will be conducted. Change gloves between items.

  5. If the fabric/clothing will be analyzed for ignitable liquid residue, do not dry it before packaging. Label a new metal paint can or nylon fire debris bag large enough for the item with identifying information, including case number, date, exhibit number, a brief description, and your name. Recover the wet fabric/clothing by carefully lifting it and placing it in a new, unused metal paint can. Leave 1/3 headspace in the can. Seal the can tightly. Place evidence tape over the top of the can, and initial and date the tape. Because the fabric/clothing has been collected wet, it must be transferred to the lab as soon as possible. Wet fabric left enclosed in an airtight container for a period of time can cause biological changes in the sample that may affect the ignitable liquid testing results. Notify the lab that the sample is wet, so they can process it promptly.

  6. If the fabric or clothing will be examined for only DNA or trace, it should be dried before collection and placed in an air-permeable container. Dry the wet fabric/clothing by placing it on clean paper. When the fabric/clothing is dry, roll it in the paper it was dried over to preserve any trace evidence that fell onto to the paper. Place the rolled paper and fabric in an air-permeable container, such as a paper bag or a box.

  7. Label the container with identifying information, including case number, date, exhibit number, a brief description, and your name.

  8. Seal the container with evidence tape and initial and date the tape.

  9. If multiple analyses are required, check with the lab to determine how to collect the fabric/clothing.

  10. Store the item in a secure location, such as a locked evidence van or your vehicle, until you are able to transport it to the laboratory. Please note that special storage may be required if the fabric or clothing may bear biological evidence, which should not be left in a hot car. Consult your laboratory for assistance.

  11. Work with the laboratory to determine the sequence of examination if you are requesting more than one kind of testing.

Laboratory testing of fabric or clothing:

Fabric can be analyzed for ignitable liquids, trace evidence (eg: glass, hairs, and foreign fibers), and DNA. If a fabric comparison is desired between known and questioned pieces of fabric, they are examined for class characteristics, such as color, construction (plies, weaves, seams), and composition (fiber content). In some cases, the manufacturer and/or retail information may be determined. A physical match may also be possible between questioned and known fabrics.

Source:

interFIRE. "Evidence Sampling for Ignitable Liquids Testing." Online Training Module, 2013:

http://www.interfire.org/training/evidencesampling.asp

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