Over 100 years ago fingerprinting
because the most accurate way to place a suspect
at the scene of the crime. The technique was revolutionary
and put many criminals behind bars. Now, however,
a newer and more accurate method is being used:
DNA testing, and it’s just as revolutionary, if
not more so.
Although DNA testing takes time--usually
several weeks because of the legwork involved in
matching base pair sequences--it is highly accurate;
in one case, the odds that the match was incorrect
were 350 million to 1! This makes DNA tests the
most accurate piece of scientific evidence a lawyer
The process is simple: two samples
are taken, one from the suspect and one from the
scene of the crime. The samples can be skin tissue,
hair, blood, semen or vaginal fluid, and really
anything else with cells in it (the two samples
don’t even have to be the same material because
all cells of the same organism have identical DNA).
Then, the DNA of both samples is extracted, studied,
and compared. If the DNA matches, then the suspect
was at the scene of the crime.
The techniques was first used in the
late 1980’s to convict a Portland, Oregon, man of
raping and impregnating his 13 year old daughter.
Tissue samples were taken from both the man and
the fetus (which had been previously aborted) and
the DNA was analyzed. The results were conclusive
and the man confessed. The test was remarkable not
only in that it provided concrete evidence, but
also because the samples compared weren’t from the
same organism (the fetus had both the man’s and
girl’s DNA, yet scientists were still able to find
Since the late ‘80’s, DNA has been
widely used in the courtroom. It was used as evidence
in the 1995 O.J. Simpson trial. It was also used
to clear deceased Sam Sheppard, the famous physician
who was accused of killing his wife in 1954, but
claimed a “bushy-haired” man did it (this true story
inspired the TV series and movie “The Fugitive”).
A DNA test proved that the blood at the murder scene
wasn’t Sheppard’s or his wife’s--meaning someone
else was there! This story is similar to countless
others: since the advent of DNA testing, dozens
of wrongly-convicted men have been pardoned and
Even DNA from animals has been used.
In one case, a murder suspect accused of killing
a couple and their dog was convicted after a DNA
test proved that the suspect’s jacket had the dog’s
blood on it. And in California, a poacher was sentenced
after a DNA test proved that his refrigerator contained
venison from eight different deer (six more than
the legal limit).
DNA testing is the most accurate form
of scientific evidence available--within millionths
of a percent! It’s allowed the justice system to
easily find the criminals--the right criminals--and
keep them from harming society.