| When
the results of DNA tests recently freed
Christopher Ochoa after he spent 12 years in a Texas prison, he became
the latest of almost a hundred prisoners whom genetic evidence cleared
of serious crime charges, not to mention the hundreds of suspects who have
been exonerated.
As
the technology continues to advance, forensic scientists and legal experts
alike are turning to this powerful biological tool more than ever before.
Genetic
blueprints
Ochoa
had an emotional reunion with his mother after his long stay in prison,
but Frank Lee Smith wasn’t as fortunate.
Smith died of cancer in prison early last year after spending 14 years
on death row for the rape and murder of a little girl. Last month, however,
DNA
tests showed he didn’t commit the crime.
| Although
the testing was done too late to save Smith, the forensic scientists who
perform DNA tests say their work can be gratifying. "One of the more satisfying
things we do is to prove that someone who’s been suspected or even arrested
of a crime has not actually committed that crime," says Robert Shaler,
director of the New York City Forensic Biology Laboratory.
It
used to be that forensic experts had to rely on fingerprints to place suspects
at crime scenes. DNA is like a fingerprint, in that everyone’s is unique,
but it’s also much more precise. "Fingerprints are found at crime scenes
all over the country but a vast majority of them are unusable, whereas
a single molecule of DNA potentially can be used to identify an individual,"
says Shaler.
A
genetic blueprint of who we are, DNA can be isolated from a variety of
materials, including blood, bone, saliva, semen, and hair. Experts begin
by isolating the DNA from samples found at the crime scene and determining
how much of it there is. |
The
identical DNA bands seen in
the
three lanes on the right are
from
one person while the bands
in
the three lanes on the left are
from
a second individual. |
| DNA
testing can be applied in a variety of ways. "One is to take a crime scene
sample and compare it to another crime scene sample and show that that
particular crime was committed by the same person," says Shaler. His laboratory
has also matched samples with the DNA of arrested suspects who are on trial,
as well as those already incarcerated.
But
those with the most to gain from DNA testing are the more than 3,000 people
on death row. Smith would have been the tenth person facing the death penalty
to be exonerated based on DNA evidence, which has only been used since
the early 90’s. |
Robert
Shaler and his lab
technician
work with DNA samples. |
Opponents
of the death penalty question why the test isn’t used more often. "The
cost of having the death penalty is absolutely enormous and the cost of
the DNA test is not particularly high, and falling," says Eric
Freedman, a law professor at Hofstra
University Law School. "And of course, if somebody is released, then
the state has no cost whatsoever."
During
the presidential campaign, George W. Bush said he supported DNA testing
if it can confirm guilt or innocence in a death penalty case. But New York
and Illinois are the only two states where death row inmates have a right
to DNA testing.
Freedman
points out that DNA testing is not a panacea. "It is an ability to get
a window on the accuracy of the criminal justice system in a small category
of cases where biological evidence exists," he says. But to those accused
or convicted of crimes, this scientific tool could make or break their
cases. For some, it could even prove to be a matter of life or death. |
