Evidence Collection Guidelines

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  • Published : February 15, 2011
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Evidence Collection Guidelines

This document provides evidence collection guidelines for the following types of evidence. Your agency's policies may vary. Please check with your supervisor if you have any questions.


Blood Stains 
Seminal Stains 
Fibers and Threads 
Flammable Liquids 
Firearms Evidence 
Tool Marks 
Questioned Documents 
Latent Fingerprints

In all cases, evidence must be photographed prior to collection attempts. At least one photo should include a scale for reference, but initial photos should be free of any markings.

Blood Stains

Blood that is in liquid pools should be picked up on a gauze pad or other clean sterile cotton cloth and allowed to air dry thoroughly, at room temperature. It should be refrigerated or frozen as soon as possible and brought to the Laboratory as quickly as possible. Delays beyond 48 hours may make the samples useless. The Industry standard is now sterile cotton swabs and cardboard swab boxes, which are then placed in an envelope. Freezing is now frowned upon, due to potential cellular damage – refrigeration is good.

•     If close to the Laboratory, deliver stained object immediately.

•     If unable to deliver to the Laboratory, or if the object must be mailed, allow the stain to air dry completely before packaging.

•     Do not heat stained material or place it in bright sunlight to dry. Hang clothing and similar articles in a room where there is adequate ventilation.

•     If not completely dry, label and roll in paper or place in a brown paper bag or box and seal and label container. Place only one item in each container. Do not use plastic containers.

Dried Blood Stains

•     On clothing, if possible, wrap the item in clean paper, place the article in a brown paper bag or box and seal and label container. Do not attempt to remove stains from the cloth.

•     On small solid objects, send the whole stained object to the Laboratory, after labeling and packaging.

•     On large solid objects, cover the stained area with clean paper and seal the edges down with tape to prevent loss or contamination. If impractical to deliver the whole object to the Laboratory, scrape the stain onto a clean piece of paper, which can be folded and placed in an envelope. Do not scrape directly into evidence envelope. Scrape blood from objects using a freshly washed and dried knife or similar tool. Wash and dry the tool before each stain is scraped off. Seal and mark the envelope. NEVER scrape dried blood, this is antiquated advice and makes it airborne, the stain should be cut out and submitted to the lab after photographs to depict its original state and location. Sterile cotton swabs, saturated with sterile water to re-wet the dried blood is the preferred method of collecting dried blood. It is then allowed to thoroughly air dry and packaged in a swab box and envelope.

•     Do not mix dried stains. Place each stain in a separate envelope.

•     Never attempt to wipe dried stains from an object using a moistened cloth or paper. Again, this is old thinking and has been changed. Sterile water should be used though and it is readily available in small single-use sealed vials.

Standard Blood Specimens

Autopsy Blood Samples 
Request that pathologist obtain the sample directly from the heart into a yellow (ACD) or purple stoppered vacutainer (some labs request both). In rare cases when no liquid blood is available, ask pathologist to collect a section of liver, bone, and/or deep muscle tissue and freeze for typing. In such cases, proceed also with collection of a secondary standard as described below.   

Blood Samples From Live Individuals  
For typing purposes, have sample drawn into yellow and purple stoppered vacutainers. Note these are distinguished from the BA tubes which have grey...
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