ENDERBY, England — Police investigating the murders of two teen-age girls near this small Midlands village are applying a new scientific technique that some predict could be the most significant breakthrough in resolving serious crime since fingerprinting was invented.
The technique involves isolating elements of the genetic structure in blood, a structure that scientists say is as individually distinctive as a fingerprint. It has enabled Leicestershire County Police investigators to confirm their initial belief that the same man raped and strangled the two 15-year-old schoolgirls, Lynda Mann and Dawn Ashworth, even though 2 1/2 years separated their deaths.
The test also led directly to the release of a 17-year-old youth who had been formally charged with one of the murders.
Now, police hope to positively identify the killer by collecting blood and saliva samples from every male between the ages 13 and 30 who lives or works in the area of three villages that surround the grasslands where the girls were attacked.
"It's technically difficult to do, but it has enormous potential," said Dr. Kevin Kelly, a University of Aberdeen biochemist who has performed the test and recently co-authored an article on the subject. "It's a breakthrough."
The voluntary testing program, which might have aroused strong controversy over constitutional and privacy issues in the United States, has been met with relatively little opposition here. This rural but close-knit society has been so shocked and frightened by the murders that peer pressure has overcome what little reluctance there has been to cooperate with the police.
Some civil libertarians, however, have voiced reservations about the technique.
Peter Thornton, a courtroom lawyer and a spokesman for the National Council for Civil Liberties, expressed concern, both about possible human error in conducting the complicated test and the implications of mass screening for a criminal such as that now under way here.
"Police have treated these volunteers like murder suspects, asking them for a photo or whether they have a criminal record," Thornton said. "At the very least we need Home Office guidelines or a (special) committee of Parliament to look at the implications of this test."
Thornton did concede that "very positive benefits" could come from the test, such as resolving paternity disputes or determining parenthood in immigration cases, "as long as there are proper controls on its use."
The technique was first developed by Leicester University geneticist Alec Jeffreys in a laboratory only a few miles from the murder scenes. It focuses on material called DNA, deoxyribonucleic acid, found in the chromosomes of all living beings. Chromosomes contain an individual's basic blueprint, determining everything from sex to eye color.
According to Jeffreys, the series of bands that make up the DNA are arranged as specifically and individually as a fingerprint, a similarity that has given his technique the name "genetic fingerprinting."
The test can be effectively done on dried blood as much as three to five years old or on dried semen up to three years old, Jeffreys said.
The chances of two people having the same DNA fingerprint are estimated at about 30 billion to one. Genetic fingerprints of parents and children are said to be similar, but not identical.
Although they are individually specific, however, Jeffreys stressed that DNA fingerprints contain no information regarding the sex or even the species of the donor.
"If you took samples from half a dozen gorillas and half a dozen people, you couldn't tell them apart," he said. "They'd just be a series of lines on an X-ray."
The technique has yet to be challenged in court, but the British Home Office has already accepted genetic fingerprinting results as evidence in a limited number of immigration cases where proof of parent-child relationship was required.
"The test is clearly of evidential value," a Home Office spokesman said.
More traditional tests, such as blood typing, already are routinely used to eliminate suspects from criminal investigations, but are much less exacting and therefore unsuited for positive identification.
The British chemical company Imperial Chemical Industries, which bought global rights to the genetic fingerprinting test, is building a special laboratory at Abingdon, near Oxford, to conduct tests commercially.
Possibly Knew Victim
The decision to do a mass sampling in the Leicestershire villages is based on evidence indicating that the murderer knew both the area and possibly his first victim.
"From all we've looked at, we strongly believe the culprit is a local man," Detective Supt. Anthony Painter, the senior investigator in charge of both cases, stated.
Because of evidence indicating that the attacker may have been a school acquaintance, police have set a relatively low age cutoff of 30.