August 14, 1998. Copyright, 1998, Graphic News. All rights reserved

THE SCIENCE BEHIND THE STAIN
By Oliver Burkeman, Science Editor

LONDON, August 14, Graphic News: IF ÔTHAT DRESSÕ proves crucial in determining whether Bill Clinton lied about his relationship with Monica Lewinsky, it will be the latest triumph for DNA fingerprinting Ð a scientific breakthrough already boasting a string of successes, from settling paternity disputes and convicting violent criminals to identifying the skeletons of murdered Russian royals.

Scientists use a technique known as polymerase chain reaction, developed in the 1980s, to reconstruct an individualÕs unique Ôgenetic fingerprintÕ from a sample of blood, saliva, semen or body tissue. The FBI, which is analysing LewinskyÕs dress for traces of presidential DNA, say the process Ð which previously carried a significant margin of error Ð now yields completely reliable results.

It was DNA fingerprinting which led to the identification of the remains of Tsar Nicholas and his family, shot dead by Bolshevik revolutionaries in 1918, in a mass grave outside Yekaterinburg in Russia. The skeletons were matched to the DNA of the TsarÕs modern-day descendants even though the remains had been covered in acid.

Serial rapist Tommy Lee Andrews, sentenced to 22 yearsÕ imprisonment in 1987, was the first American to be convicted on the basis of DNA evidence. Earlier this year, German police searching for the murderer of an 11-year-old girl took saliva samples from 16,400 local men Ð resulting in the identification of a man who confessed to the killing and admitted to another murder.

The FBIÕs DNA laboratory received the dark blue dress on July 30, and should by now know whether the stain is of human origin. But establishing whether it is ClintonÕs could take weeks more, and will require him to provide a DNA sample. The results will be delivered only to the office of Independent Counsel Kenneth Starr Ð allowing Starr to time the disclosure to cause maximum embarrassment to Clinton, due to testify before the grand jury from Monday.

AmericaÕs comedians have rushed to fill the vacuum left by the FBIÕs tight-lipped silence. One joke Ð playing on the PresidentÕs love affair with fast food Ð suggests that the stain is really McDonaldÕs special sauce, while late-night talk show host Jay Leno says Clinton wonÕt object to providing DNA to the FBI for comparative purposes Ð Ôas long as he gets to pick the intern thatÕs going to collect the sampleÕ.

Sources: Reuters, CNN.com