Hair Evidence
and Mitochondrial DNA TestingMark Hanson has written an
interesting article in the May, 1998 issue of the ABA Journal entitled
"A Comeback For Hair Evidence." The article discusses a new technique
for testing hair samples for DNA called mitochondrial DNA testing.
Conventional DNA testing involves the extraction of genetic material
from the nucleus of a cell. By contrast, mitochondrial DNA testing uses
DNA extracted from mitochondria, the energy-producing material found in
the portion of the cell that surrounds the nucleus. Since hairs found at
a crime scene have, until now, been largely untestable for DNA, hair
analysis, with its inherent shortcomings, has been used less frequently
over the years by crime scene investigators.
The FBI developed mitochondrial DNA testing for use in criminal
investigations, and apparantly has done all of the testing to date.
In my view, mitochondrial DNA testing presents some interesting
possibilities for defense counsel. Because everyone loses some hair
every day, almost every crime scene will contain some hair from persons
other than the perpetrator and the victim. Mitochondrial DNA testing may
now offer proof that someone other than the accused was present at the
crime scene.
