NCJ Number
195851
Journal
Law Enforcement Technology Volume: 29 Issue: 6 Dated: June 2002 Pages: 120,122-124,125
Date Published
June 2002
Length
5 pages
Annotation
A new forensic technique in development at the National Institute of Standards and Technology (NIST) may help positively identify criminals by chemical components left deposited on hair.
Abstract
Currently, hair found at crime scenes cannot be matched reliably to any specific person. NIST, however, is testing a process that may become as reliable as fingerprints in uniquely identifying individuals. The new NIST technique, which uses a technology called supercritical fluid extraction (SFE) -- a process similar to one used to decaffeinate coffee -- allows chemical components of hair to be extracted by SFE and identified by using gas chromatography/mass spectrometry (SFE-GC/MS). The process relies on the fact that chemicals can be deposited on the hair either naturally (such as cholesterol) or artificially (such as shampoos, conditioners, sprays, and oils). The system permits the characterization of surface components of hair, information that might complement data obtained from more conventional microscopic examination. Currently, it takes DNA to make positive identification matches with hair, but hairs found at a crime scene can be matched to a specific person with certainty only if the hair has a root. Hair roots often have sufficient nuclear DNA in them to permit an analysis. The NIST technology will eventually complement rather than replace mitochondrial DNA analysis of hair. The same hair can be subjected to both types of analysis. The question that remains to be answered is how unique is the chemical composition of hair between individuals. Much of the effectiveness and usefulness of the NIST technology will depend on additional studies that profile human hair and how it chemically differs from one person to another.