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Molecular Biology technique most famous for its involvement in the OJ Simpson trial. It involves amplifying a genomic DNA sample using PCR, then digesting that sample with a Restriction Enzyme. This chops the DNA into fragments which are then sorted using gel electrophoresis. The pattern produced is distinctive, with the most commonly quoted percentage of a match being 1 in 16 million. Its limitations are that the DNA sample must be from only one source, and it has relatively low accuracy when compared to DNA sequencing.

Also known as Restriction fragment length polymorphisms.
DNA fingerprinting uses restriction fragment length polymorphisms. Compares and contrasts, even.

They are popular as paternity tests; half of your chromosomes come from your mother and half come from your fathers, so approximately half of the lines on your DNA fingerprint come from each parent, and no line in your DNA fingerprint lacks a counterpart in one of your parent's DNA fingerprints (barring the small chance of mutation - in the gametes or zygote, though if I was feeling really anal I'd qualify this statement - causing a restriction site(s) for the restriction enzyme used in the fingerprinting to appear/disappear). And if some of the lines on your DNA fingerprint are doubled/tripled/quadrupled up exactly then your parents are probably related.

Still not scientific enough. Phrase it again.

The first case solved using DNA fingerprinting contains more twists than an average Hollywood thriller.

In 1983, 15-year old Lynda Mann was raped and murdered in the Narborough area near Leicester, in England. The forensic experts called to examine the evidence could reveal only that the murderer had type A blood and a somewhat rare combination of enzymes, but these informations were not enough to point to anybody - more than 10% of the adult male population matched that profile.

Without other leads, the case was sadly destined to remain unsolved.

Three years later there was an identical crime in the area - the police found the body of Dawn Ashworth, also 15. She had been sexually assaulted and strangled. The semen samples pointed to the same blood type as in the Lynda case, so the investigators were sure that the assailant was the same. This time they focused on a local boy, Richard Buckland; after a long questioning he confessed the homicide of Dawn, but denied any involvement with the murder of Lynda.

The investigators wanted to close that case too, so they decided to contact Dr. Alec Jeffreys at nearby Leicester University, who had been in the news lately - he had discovered a new technique for tracking down genetic diseases. The technique was called RFLP, and one of its side effects was that it could be used to match a man to his DNA with great accuracy.

He agreed to help the police, and they sent him DNA samples from the two murder cases and from Buckland. Dr. Jeffreys was able to confirm that the two girls had indeed been murdered by the same man, but that man wasn't Buckland.

Richard Buckland has the dubious honour of being the first person in the word to be acquitted thanks to DNA fingerprinting - given the evidence and the confession, he would have certainly been convicted a decade earlier.

Back to square one, the police tried a stunt that would have been impossible in the States: they asked every male resident of the area to provide a blood or saliva sample, to be eliminated from the list of the suspects. 5000 men - all the residents in the presumed age bracket of the murder - "volunteered" to be tested. They were considered guilty until they proved their innocence.

The mass screening took six months to complete, and in the end - nothing come out. The DNA fingerprinting excluded all those who had been tested. The "unsolved cases" cabinet opened once again.

The investigators finally got their lucky break a year later, when a woman overheard a conversation by a Mr. Ian Kelly. Kelly had apparently helped a local baker who didn't want to be tested, giving a blood sample in his name.

The baker was arrested and tested, and his DNA profile matched the samples taken from both victims. He has been sentenced to life imprisonment - and he is the first person to be convicted thanks to DNA fingerprinting.

The name of the devilish murderer was Colin Pitchfork. Fate, it seems, is not without a sense of irony.

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