Trace Evidence in Criminal Cases

Any evidence that has no category to fit under goes in the trace evidence category. It can be hair, fibers, glass, paint, primer gunshot residue, fire debris, explosives, and any other unusual thing found at the crime scene. (Lewis, 2004) According to Wikipedia (2007), Evidence found at a crime scene can include botanical material, explosive residue, and arson evidence. "Trace evidence is based on Locard's exchange principle which contends that every contact no matter how slight will leave a trace." (Wikipedia.com, 2007)

Trace evidence is categorized in two ways, class evidence and individual evidence. Class evidence does not eliminate the likelihood of the presence of the other object of material, it limits them. According to sccja.org( 2007), the more class characteristics, the more valuable the investigation. Class evidence can place an object in a group, like a small section of a zipper. (Lewis, 2004) Individual evidence shows an objects' uniqueness. It can identify and exclude that object from any other. Individual evidence can specifically place things to a person or place to the exclusion of all others, according to Lewis (2004). Examples would be fingerprint impressions, and DNA.

Evidence can be transferred directly or indirectly. Transfer evidence can be lost quickly if the person is moving around or washes their cloths, according to FBI.gov (2007). On a murder victim, clothing must be handled carefully to maintain the integrity of the transfer evidence. Lewis (2004) explains transfer evidence as evidence that is transferred from one object to another. Direct transfer evidence is where the trace evidence is transferred directly from the object to another object. Indirect transfers happen when trace evidence goes through a middle man, so to speak. It happens when the evidence is transferred from an object then to a person, then to another object.

Although the evidence is very small, trace evidence is a very important piece to the puzzle in any investigation. It can give clues to who was there, what weapon was used, and many other possible leads can come from it. It must be properly documented, and the chain of custody must be followed at all times. (Lewis, 2004)

References

1) Lewis, J. (2004). Criminalistics For Crime Scene Investigators: Criminal Investigations

Series. Law Tech Publishing Co.

2) http://www.wikipedia.org/wiki/Trace_evidence. Retrieved June 20, 2007.

3) http://www.sccja.org/csr-properties.htm. Retrieved June 20, 2007.

4) http://www.fbi.gov/hq/lab/fsc/backissue/20Transfer%20and%20Persistance. Retrieved June

21, 2007.