Patterned Evidence

Patterned evidence is one of the most commonly recovered forms of evidence, according to the National Institute of Justice (NIJ).[1] Impression evidence, which is a type of patterned evidence, forms when objects come into contact with one another, leaving either a two- or three-dimensional mark. A fingerprint on a hard surface is an example of a two-dimensional mark, while a tire impression in mud is an example of a three-dimensional impression. Patterned evidence is analyzed and matched in order to link a suspect or tool to a crime. Unique characteristics, such as cuts or nicks, within a piece of patterned evidence allows for stronger matching, such as when a crowbar is used on a windowsill. The matching of patterned evidence from an unknown sample from the crime scene and known sample from the suspect is done by a trained examiner, who must identify unique characteristics and determine whether the samples may have come from the same source. Handwriting, fingerprints, tool marks, ballistics, bloodstains, and other impressions such as shoe prints or tire marks are examples of patterned evidence. Fingerprint evidence is a common form of patterned evidence; potential matches can be found using a fingerprint database like the FBI’s Integrated Automated Fingerprint Identification System (IAFIS).

Refer to chapter 5 of the 2009 NAS report on forensic science for further descriptions of disciplines: friction ridge analysis, tool mark and firearms identification, bloodstain pattern analysis, and other pattern/impression evidence: shoeprints and tire tracks.[2] Refer to chapter 10 of the 2009 NAS report on forensic science for more information about automated fingerprint identification systems.[3]

Resources

Reviews of Current Trends in Forensic Science

Forensic science is a constantly progressing field due to the advent of new instruments, techniques, and novel interpretations. Considering the evolving nature of the discipline, it is imperative that legal professionals and scientists remain aware of modern methods and advancements in forensic science. Emily Lennert with the UCF National Center for Forensic Science regularly reviews journal articles related to forensic science. Those reviews can be found here with the accompanying citation to the journal article for further reading.

Videos

Forensic Textile Fiber Identification Using Detergent Fluorescence – Dr. Nirvani Mujumdar

Litigation Challenges and Friction Ridge Evidence  – Brendan Max

Firearms – Chris Robinson

[1] Impression and Pattern Evidence. http://www.nij.gov/topics/forensics/evidence/impression/pages/welcome.aspx (accessed July 11, 2016).

[2] Strengthening forensic science in the United States: a path forward; National Academies Press: Washington, D.C., 2009.

[3] Id.

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