Dna And Crime

DNA and Crime

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 probably 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. 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 s...

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...ing 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 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.