Using DNA Evidence
Given the high profile of DNA evidence during the O.J. Simpson trial, most people know that DNA profiles are used by criminal investigators to:- Prove guilt - Matching DNA profiles can link a suspect to a
crime or crime scene.
- Exonerate an innocent person - Innocent people have been freed from death row in the United States based on DNA evidence. So far, DNA evidence has been almost as useful in excluding suspects as in fingering and convicting them; about 30 percent of DNA profile comparisons done by the FBI result in excluding someone as a suspect.
- Paternity testing and other cases where authorities need to
prove whether or not individuals are related - One of the more infamous
paternity cases of late revolved around a 1998 paper in the journal
"Nature" that studied whether or not Thomas Jefferson, the third
president of the United States, fathered children with one of
his slaves.
Photo courtesy Genelex, Inc
DNA evidence can pinpoint whether or not someone
is a parent.
- Identification of John or Jane Does - Police
investigators often face the unpleasant task of trying to identify a
body or skeletal remains. DNA is a fairly resilient molecule, and
samples can be easily extracted from hair or bone tissue; once a DNA
profile has been created, it can be compared to samples from families
of missing persons to see if a match can be made. The military
even uses DNA profiles in place of the old-school dog tag. Each new
recruit must provide blood and saliva samples, and the stored samples
can subsequently be used as a positive ID for soldiers killed in the
line of duty. Even without a DNA match to conclusively identify a body,
a profile is useful because it can provide important clues about the
victim, such as his or her sex and race.
- Studying the evolution of human populations -
Scientists are trying to use samples extracted from skeletons and from
living people around the world to show how early human populations
might have migrated across the globe and diversified into so many
different races.
- Studying inherited disorders - Scientist also study the DNA fingerprints of families with members who have inherited diseases like Alzheimer's Disease to try and ferret out chromosomal differences between those without the disease and who are have it, in the hopes that these changes might be linked to getting the disease.
For more information about DNA evidence, check out the links on the next page.
