Dawn Ashworth, 15, left a friend's house last July to walk to her home in Enderby, a village in England's East Midlands. She never made it. Two days later her body was found; she had been raped and strangled. Soon after, police arrested a 17-year-old youth in connection with that killing and an earlier, similar murder.

But three months later, convinced that the suspect was innocent of both crimes, the police freed him. How could they be so sure? By using the new technique of DNA fingerprinting they had proved that man was innocent. This month the police began using the test on blood from 2,000 Midlands men, hoping that if one of them is guilty, his DNA print will give him away.

The test involves comparing the DNA of blood or hair roots found at the scene with the DNA of a suspect. What makes it foolproof is that no two people (other than identical twins) have the same genetic characteristics. While considering this fact in 1983, Alec Jeffrets, a geneticist at the University of Leicester in England, realized it might be the basis for an important new tool in criminal investigations. The DNA from each individual, he found, formed a unique pattern — in effect a DNA fingerprint.

In the Midlands case, Jeffreys established that the DNA pattern of the 17-year-old suspect did not match those obtained during the murder investigations. The patterns of each of the 2,000 Midlands men will undergo similar scrutiny. But that may take a while. Each test involves a complicated series of steps over a period of 2 1/2 weeks. Still, Jeffreys believes, with further refinements, and despite $ 300 price tag, the test will more than pay for itself in criminal investigations.

(«Moscow News» from «Times»)