The science of biometrics involves identification of people based on physical and behavioral characteristics. This includes facial recognition software, voice identification software and retina scanning. Biometrics is used commonly in forensic science with fingerprinting, handwriting analysis, hair analysis and blood identification.
Forensic Identification with Tattoos
Skin markings like scars, birthmarks and tattoos are considered soft biometrics, easily measurable physical characteristics that can change. Tattoos are becoming more common with estimates that approximately 36% of people between 18 and 29 have at least one tattoo. Most are specific to the individual, though many social groups adopt tattoos of similar design to designate membership. This is very common among gang members. Tattoos can give information on social characteristics such as time in prison, number of crimes committed and ethnic affiliations.
Tattoos have been used for identifying bodies in mass disasters like 9/11 and homicides. This is often necessary when partial remains are found or other identifying biometrics like fingerprints are removed. Residual markings from tattoos remain in the skin even after burns or decomposition. Tattoos are also used to identify suspects in custody who may be using a false name.
In the past, forensic investigators have kept large notebooks containing tattoo photos, which later gave way to searchable computer databases with tattoo characteristics. Both are unwieldy and require significant search time to find a match.
Tattoo ID Software from Michigan State University
Biometric scientists from Michigan State University developed software to aid in photographic tattoo identification. Tattoo images taken by law enforcement can be matched to existing images in photo databases which is much more efficient than a text-based search. The tattoos are matched using complex mathematical algorithms that compare similar characteristics. This allows matching when pictures may be blurred, such as those taken by a surveillance camera. Images are compared based on color, texture and shape of the tattoo.
Existing photo databases can be linked to the software, providing information from law enforcement agencies all over the United States. As of 2009, the system contained 64,000 digital tattoo images obtained from the Michigan State Police.
The software has been licensed to MorphoTrak, a biometric technology company, which also provides fingerprint and face-matching recognition software to various law enforcement professionals in North America.
Houck, Max. Biometrics and Forensic Science: What’s the Difference? Biometrics.org Accessed February 4, 2010.
Jain, Anil. Tattoo-ID: Automatic Tattoo Image Retrieval for Suspect and Victim Identification Biometrics. Michigan State University. Accessed February 4, 2010.
Jain, Anil. Scars, Marks and Tattoos: a Soft Biometric for Identifying Suspects and Victims Accessed February 4, 2010.
MorphoTrak Product Website Accessed February 4, 2010.