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Collection and Preservation of Evidence

George Schiro

Once the crime scene has been thoroughly documented and the locations of the evidence noted, then the collection process can begin. The collection process will usually start with the collection of the most fragile or most easily lost evidence. Special consideration can also be given to any evidence or objects which need to be moved. Collection can then continue along the crime scene trail or in some other logical manner. Photographs should also continue to be taken if the investigator is revealing layers of evidence which were not previously documented because they were hidden from sight.

Most items of evidence will be collected in paper containers such as packets, envelopes, and bags. Liquid items can be transported in non-breakable, leakproof containers. Arson evidence is usually collected in air-tight, clean metal cans. Only large quantities of dry powder should be collected and stored in plastic bags. Moist or wet evidence (blood, plants, etc.) from a crime scene can be collected in plastic containers at the scene and transported back to an evidence receiving area if the storage time in plastic is two hours or less and this is done to prevent contamination of other evidence. Once in a secure location, wet evidence, whether packaged in plastic or paper, must be removed and allowed to completely air dry. That evidence can then be repackaged in a new, dry paper container. UNDER NO CIRCUMSTANCES SHOULD EVIDENCE CONTAINING MOISTURE BE PACKAGED IN PLASTIC OR PAPER CONTAINERS FOR MORE THAN TWO HOURS. Moisture allows the growth of microorganisms which can destroy or alter evidence.

Any items which may cross contaminate each other must be packaged separately. The containers should be closed and secured to prevent the mixture of evidence during transportation. Each container should have: the collecting person's initials; the date and time it was collected; a complete description of the evidence and where it was found; and the investigating agency's name and their file number.

Each type of evidence has a specific value in an investigation. The value of evidence should be kept in mind by the investigator when doing a crime scene investigation. For example, when investigating a crime he or she should spend more time on collecting good fingerprints than trying to find fibers left by a suspect's clothing. The reason is that fingerprints can positively identify a person as having been at the scene of a crime, whereas fibers could have come from anyone wearing clothes made out of the same material. Of course if obvious or numerous fibers are found at the point of entry, on a victim's body, etc., then they should be collected in case no fingerprints of value are found. It is also wise to collect more evidence at a crime scene than not to collect enough evidence. An investigator usually only has one shot at a crime scene, so the most should be made of it.

The following is a breakdown of the types of evidence encountered and how the evidence should be handled:


Fingerprints (also includes palm prints and bare footprints) are the best evidence to place an individual at the scene of a crime. Collecting fingerprints at a crime scene requires very few materials, making it ideal from a cost standpoint. All non-movable items at a crime scene should be processed at the scene using gray powder, black powder, or black magnetic powder. Polaroid 665 black and white film loaded in a Polaroid CU-5 camera with detachable flash should be used to make one-to-one photographs of prints which do not readily lift. All small transportable items should be packaged in paper bags or envelopes and sent to the crime lab for processing. Because of the "package it up and send it to the lab" mentality, some investigators skim over collecting prints at a crime scene. Collecting prints at the crime scene should be every investigator's top priority. Fingerprints from the suspect as well as elimination fingerprints from the victim will also be needed for comparison (the same holds true for palm and bare footprints).

Bite Marks

Bite marks are found many times in sexual assaults and can be matched back to the individual who did the biting. They should be photographed using an ABFO No. 2 Scale with normal lighting conditions, side lighting, UV light, and alternate light sources. Color slide and print film as well as black and white film should be used. The more photographs under a variety of conditions, the better. Older bitemarks which are no longer visible on the skin may sometimes be visualized and photographed using UV light and alternate light sources. If the bitemark has left an impression then maybe a cast can be made of it. Casts and photographs of the suspect's teeth and maybe the victim's teeth will be needed for comparison. For more information consult a forensic odontologist.

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This Month's Featured Resource on the Crime Scene Investigator Network Website

This revised and updated edition is the result of a collaborative effort to present the most up-to-date information about the issues confronting death investigators today. The death investigator is the eyes and ears of the forensic pathologist at the scene. It is hoped that these guidelines, reflecting the best practices of the forensic community, will serve as a national standard.

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Adams County Sheriff's Office, Commerce City, Colorado, USA

Final Filing Date: January 24, 2019
The Criminalist assigned to the Laboratory Unit is responsible for responding to crime scenes to collect, preserve, and document evidence, and to evaluate, examine, analyze and identify evidence collected. (physical evidence, photographs, video, sketches, documentation)
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Crime Scene Specialist
Austin Police Department, Austin, Texas, USA

Final Filing Date: January 29, 2019
Responds to crime and accident scenes, evaluates the scene and conducts searches for evidence utilizing disciplines related to crime scene investigation. Measures and/or photographs crime scenes, evidence, etc. Documents, collects, packages, preserves, and processes evidence. Utilizes alternate light sources, chemical and physical processes, scientific methods and equipment for the detection and collection of evidence.
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Investigative Technician I/II
Shasta County Sheriff's Office, Redding, California, USA

Final Filing Date: February 15, 2019
Searches for, collects, and preserves evidence at crime scenes for laboratory analysis; photographs crime scenes, suspects, or evidence; takes, compares, and identifies fingerprints. Develops and preserves latent fingerprints; conducts latent identification and analysis with the ULW workstation; collects, preserves, compares, and attempts to identify evidence such as blood, hair, fibers, cloth, wood, paint, and glass fragments.
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Forensic Scientist Trainee - Controlled Substances
Virginia Department of Forensic Science, Roanoke, Virginia, USA

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Cyber Crimes Technician
Anchorage Police Department, Anchorage, Alaska, USA

Final Filing Date: January 28, 2019
Assist Detectives with case development, the retrieval of criminal justice information, and provide limited aspects of clerical support to the unit supervisor and commissioned personnel assigned to the Anchorage Police Department Cyber Crime Unit. Support of technical investigations including analysis and documentation of digital data, evidence handling, research and administrative support, court testimony, and INTERNET safety presentations.
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DuPage County Sheriff's Office, Wheaton, Illinois, USA

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Performs the development (physical and chemical processing), digital photography, analysis, AFIS/NGI searching, comparison, evaluation and verification of known and latent print evidence. Makes conclusions, and formulates opinions based on examinations performed and reports those findings.
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