ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

DNA FingerprintingDNA fingerprinting is an important tool in the arsenalof forensic investigators and intelligence officers. In an erawhen plastic surgery can be used to alter a terrorist’sappearance, DNA fingerprinting allows for positive identificationnot only of body remains, but also of suspects incustody. DNA fingerprinting can also link physical evidencefrom incidents that occur in different parts ofthe world.Sir Alec Jeffreys at the University of Leicester developedDNA fingerprinting in the mid 1980s. The sequenceof nucleotides in DNA is similar to a fingerprint, in that it isunique to each person. DNA fingerprinting is used foridentifying people, studying populations, and forensicinvestigations.Historical Uses ofDNA FingerprintingJeffreys was first given the opportunity to demonstratethe power of DNA fingerprinting in March of 1985 when heproved a boy was the son of a British citizen and should beallowed to enter the country. In 1986, DNA was first usedin forensics. In a village near Jeffreys’ home, a teenage girlwas assaulted and strangled. No suspect was found, althoughbody fluids were recovered at the crime scene.When another girl was strangled in the same way, a 19-year-old caterer confessed to one murder but not theother. DNA analysis showed that the same person committedboth murders, and the caterer had falsely confessed.Blood samples of 4582 village men were taken,and eventually the killer was revealed when he attemptedto bribe someone to take the test for him.The first case to be tried in the United States usingDNA fingerprinting evidence was of African-AmericanTommie Lee Edwards. In November 1987, a judge didnot permit population genetics statistics that comparedEdwards to a representative population. The judge fearedthe jury would be overwhelmed by the technical information.The trial ended in a mistrial. Three months later,Andrews was on trial for the assault of another woman.This time the judge did permit the evidence of populationgenetics statistics. The prosecutor showed that the probabilitythat Edwards’ DNA would not match the crimeevidence was one in ten billion. Edwards was convicted.DNA fingerprinting has been used repeatedly to identifyhuman remains. In Cardiff, Wales, skeletal remains ofa young woman were found, and a medical artist was ableto make a model of the girl’s face. She was recognized by asocial worker as a local run-away. Comparing the DNA ofthe femur of the girl with samples from the presumptiveparents, Jeffreys declared a match between the identifiedgirl and her parents. In Brazil, Wolfgang Gerhard, who haddrowned in a boating accident, was accused of being thenotorious Nazi of Auschwitz, Josef Mengele. Disinterringthe bones, Jeffreys and his team used DNA fingerprintingto conclude that the man actually was the missing Mengele.Encyclopedia of Espionage, Intelligence, and SecurityIn addition to forensics, DNA has been used to unitefamilies. In 1976, a military junta in a South Americancountry killed over 9000 people, and the orphaned childrenwere given to military couples. After the regime wasoverthrown in 1983, Las Abuelas (The Grandmothers)determined to bring these children to their biologicalfamilies. Using DNA fingerprinting, they found the familiesof over 200 children.DNA has been used to solve several historical mysteries.On July 16, 1918, the czar of Russia and his family wereshot, doused with sulfuric acid, and buried in a massgrave. In 1989, the site of burial was uncovered, and bonefragments of nine skeletons were assembled. DNA fingerprintingexperts from all over the world pieced togetherthe puzzle that ended in a proper burial to the Romanovroyal family in Saint Petersburg in 1998.The Mechanics ofDNA FingerprintingThe nucleus of every cell in the human body containsdeoxyribonucleic acid or DNA, a biochemical moleculethat is made up of nearly three-billion nucleotides. DNAconsists of four different nucleotides, adenine (A), thymine(T), guanine (G), and cytosine (C), which are strung togetherin a sequence that is unique to every individual.The sequence of A, T, G, and C in human DNA can befound in more combinations or variations than there arehumans. The technology of DNA fingerprinting is basedon the assumption that no two people have the same DNAsequence.The DNA from a small sample of human tissue can beextracted using biochemical techniques. Then the DNAcan be digested using a series of enzymes known asrestriction enzymes, or restriction endonucleases. Thesemolecules can be thought of as chemical scissors, whichcut the DNA into pieces. Different endonucleases cut DNAat different parts of the nucleotide sequence. For example,the endonuclease called SmaI cuts the sequence of nucleotidesCCCGGG between the third cytosine (C) and thefirst guanine (G).After being exposed to a group of different restrictionenzymes, the digested DNA undergoes gel electrophoresis.In this biochemical analysis technique, test samples ofdigested DNA are placed in individual lanes on a sheet ofan agarose gel that is made from seaweed. A separatelane contains control samples of DNA of known lengths.The loaded gel is then placed in a liquid bath and anelectric current is passed through the system. The variousfragments of DNA are of different sizes and differentelectrical charges. The pieces move according to their sizeand charge with the smaller and more polar ones travelingfaster. As a result, the fragments migrate down the gel atdifferent rates.After a given amount of time, the electrical current inthe gel electrophoresis instrumentation is shut off. The gelis removed from the bath and the DNA is blotted onto a337