Deoxyribonucleic Acid - the fingerprint of life also know as DNA was first mapped out in
the early 1950's by British biophysicist, Francis Harry Compton Crick and American
biochemist James Dewey Watson. They determined the three-dimensional structure of DNA,
the substance that passes on the genetic characteristics from one generation to the next.
DNA is found in the chromosomes in the nucleus of a cell.
"Every family line has it's own unique pattern of restriction-enzyme DNA fragments.
This variation in patterns of DNA fragments found in human genetic lineages is called
'restriction-fragment length polymorphism'(RFLP). (Louis Levine, ?) Because each
person, except for identical twins(which have the exact same DNA), is formed from two
family lines the pattern of sizes of the fragments from an individual is unique and can
serve as a DNA fingerprint of that person. These 'fingerprints' have became very
important in identifying criminals in a number of violent crimes where the victims aren't
able to. Blood or semen stains on clothing, sperm cells found in a vaginal swab taken
after a rape, or root hairs are all available for analysis. Although other body tissues
such as skin cells and saliva can provide genetic information about a person for Forensic
Science purposes, blood is the most useful source of inherited traits. If the DNA
fingerprints produced from two different samples match, the two samples pr
obably came from the same person.
Here are some examples of court cases where DNA plays an important roll in the outcome
of the trial.
----Hauppauge N.Y.---After 11 years in prison for rape Kerry Kotler cried tears of joy
becoming one of the first convicts in the United States to be freed by DNA technology.
- 1 -
At a banquet held for Kotler he received a standing ovation from the guest's of his
lawyer, Barry Schech and Peter Neufeld, who would later use their DNA expertise to help
free O.J. Simpson.
Now the very weapon used to free Kotler will be used against him and instead of his
lawyers praising DNA testing they will be trying to tear it down. Four years after being
released from prison Kotler was charged with another rape and the DNA test matched him to
the semen found on the victims clothing. Posing as a police officer he forced a 20 year
old college student off the highway and raped her. A partial license plate number and a
description of the car led them to Kotler. The semen matched Kotler's blood and the
chances of the semen being somebody else's is one to 7.5 million. Also, dog hairs on
the victims clothing matched hairs from Kotler's German shepherd. Kotler, 37, is free on
$25000 bail and could get up to 50 years in jail if convicted of rape and kidnapping.
----Anamosa, Iowa---22 year old Cathy Jo Bohlken was sexually assaulted and murdered.
Genetic evidence from fluid taken from her body points to an 18 year old named Travis
Jamieson. Bohlkan's body was found DEC 26, 1993 on the floor of her duplex with a bag
over her head and her hands wrapped with duct tape. Autopsy shows she died of multiple
stab wounds. The search of a pick-up truck registered to Jamieson's parents revealed a
utility knife and a "red-brown stain" on the steering wheel.
(http://www.wcinet.com/th/news/th0208/stories/1355.htm)
----Norman, Okla---Thomas Webb III was released after more than 13 years in prison for a
1982 rape. DNA testing was not available at the time so Gale Webb, Thomas' wife, pushed
- 2 -
authorities to use DNA genetic profiling on the 14 year old evidence. These DNA tests
ruled him out as a suspect. (http://www.wcinet.com/th/news/th0525/stories/12284.htm)
----Santa Ana, Calif---Kevin Lee Green cried as the judge apologized for the mistake and
freed him from prison after nearly 17 years. He was convicted of killing his unborn baby
and nearly beating his wife to death.
He was released as authorities prepared to charge a convicted rapist with the murder of
Green's unborn child. The reversal of Green's conviction came after another man
confessed and his statement was backed up by DNA technology not available in 1980. He
was sent to prison on the testimony of his wife who at first didn't remember the attack
but that her memory suddenly returned as she read a baby magazine. She testified that
her husband severely beat her because she refused sex. Green insisted that he left to
get a cheeseburger and came home to see a man leaving in a van. Authorities now believe
the attacker was Gerald Parker, 41, who owned a van at the time. He is suspected to be
in the "bedroom basher" serial killings in Orange County in 1978 and 1979.
(http://www.wcinet.com/th/news/th0622/stories/15897.htm)
----San Francisco---Theodore Kaczynski, 54, has been jailed in Helena, Mont. since his
arrest April 3rd at the mountain cabin where he spent most of his time since quitting his
job at the University of California in 1969. The former math professor has been charged
with possession of bomb-making material. Kaczynski, the suspected Unabomber is blamed
for 3 deaths and 23 injuries in an 18 year bombing spree that begun in 1978. DNA tests
of saliva found on two letters-one sent by the Unabomber and one by Kaczynski to his
family-
- 3 -
showed a genetic link. An FBI investigation found common phrases and misspellings
between his writings and documents say were written by the Unabomber. A search of his
cabin revealed the original copy of the Unabomber's 35000 word anti-technology manifesto,
a typewriter used on the manifesto, bombs, bomb parts and detonators.
(http://www.wcinet.com/th/news/th0615/stories/14962.htm)
The accuracy of DNA fingerprinting has been challenged for many reasons. One reason is
because DNA segments rather than complete DNA strands are fingerprinted, a DNA
fingerprint may not be unique. There have been no large scale research to confirm the
uniqueness of DNA fingerprints. Also, DNA fingerprinting is often done in private
laboratories that may not follow uniform testing standards and quality controls, and
since humans must interpret the test, human error could lead to false results. DNA
fingerprinting is expensive, so suspects who are unable to provide their own DNA experts
may not be able to adequately defend themselves against charges based on DNA evidence.
There are two methods which can be used to test DNA. "The older one called
'restriction-fragment length polymorphism' (RFLP) takes up to two weeks to complete and
requires a larger supply of high quality, uncontaminated DNA. The good thing about this
test is that it finds the 'random repeats'. These extra chemical units give everyone's
DNA a unique pattern. The newer method is called Polymerase Chain Reaction (PCR). This
system uses an enzyme that can be directed towards regions of DNA known to contain
variations. The results can be printed out in a series of blue dots. The good thing
about this method is that it can be completed in a few days and it only requires a small
amount of
- 4 -
DNA, even if it has begun to degrade and deteriorate. Although PCR is faster and easier
it
does have its drawbacks. The old method finds rarely repeated characteristics while PCR
finds genetic features shared by many people. That means that the older method might
show one person in a billion is likely to have the same DNA as a suspect while PCR shows
that the same characteristics may be shared by as many as one in a thousand.(Nichols,
P58)
The discovery of DNA has led to tremendous advances in solving crimes but there is still
a lot to learn. The technology of DNA is still in it's infancy and as it develops and as
lab procedures become standardized DNA will be an even more powerful force in the
courtroom.
|