When the 57-year-old Alzheimer's victim came home from day-care at a Tacoma, Wash., hospital, her disheveled clothes made her daughters suspect that she had been raped. Their fears were confirmed when a medical examination of the woman, who remembered nothing, showed semen.
Law enforcement officials immediately had a suspect: Alan J. Haynes, 34, the day-care center's van driver. He was the only man who had been alone with the woman.
But there were no witnesses or fingerprints to link him to the crime.
So authorities sent a semen sample taken from the woman and a blood sample taken from Haynes to a laboratory for a controversial type of analysis called genetic fingerprinting. Using sophisticated genetic engineering techniques, forensic scientists compared the deoxyribonucleic acid (DNA) in the sperm to DNA from Haynes' blood and found them to be identical.
Confronted with this evidence, Haynes pleaded guilty in December, according to Pierce County deputy prosecutor Barbara Corey-Boulet. Haynes is to be sentenced Jan. 29.
His case is among a handful in the United States in which genetic fingerprinting, developed only about two years ago, has been used to prosecute a criminal suspect. But the number of cases is increasing steadily and experts believe the technique's unique capability to identify a perpetrator with virtual certainty will ensure its wide use in the future.
The technique is a significant advance over fingerprinting or matching blood proteins. The latter approach, because of its lack of specificity, can only exonerate a suspect or show that he may have committed the crime.
"It's a giant step forward," said Barry Albert, an Oklahoma County, Okla., assistant district attorney who intends to rely on evidence obtained by the technique in a rape trial scheduled to begin on Monday.
But the increasing use of genetic fingerprinting is also raising questions about the reliability of the technique and about the ability of police laboratories that may eventually use it.
Even before the technique came along, many such laboratories already were being criticized for hiring poorly trained personnel and for sloppy handling of evidence. Now critics fear that such personnel would not be able to adequately perform the sophisticated techniques required for DNA analysis.
Criminal defense attorneys also argue that prosecutors may be moving too fast by introducing genetic fingerprinting evidence in trials before its reliability has been thoroughly established.
"I don't think we've satisfied all those demands yet," conceded Cecil Hider, manager of the California Criminalistics Institute, part of the state Department of Justice in Sacramento.
"We are very concerned that some jurisdiction (in California) will prematurely introduce genetic fingerprinting results and establish bad case law that might adversely affect future cases," Hider said.
To reduce this possibility, the Department of Justice is bringing together criminologists and prosecutors from throughout the state for a meeting today at the Los Angeles Airport Marriott to discuss use of the technique.
"Nobody has seriously challenged the admissibility of DNA analysis yet," Hider said, "but it's certainly going to happen. We want to have all our bases covered when it does."
Most forensic techniques, such as fingerprinting, blood typing and hair analysis, have gradually gained acceptance in the courtroom. But others, such as the polygraph, remain controversial.
So far, trial courts have accepted evidence obtained by genetic fingerprinting in the few cases that have been tried. As yet, no prosecutor in California has attempted to introduce such evidence in a criminal trial.
Genetic fingerprinting was developed in 1985 by geneticist Alec Jeffreys and his colleagues at the University of Leicester in England. Jeffreys found that DNA--which serves as a blueprint for all living organisms--contains many short regions that are unique in composition and size for every human except identical twins.
Jeffreys then developed a technique that, in essence, involves extracting the DNA from a specimen of blood, semen or tissue and chemically chopping the DNA into short fragments. When the fragments are separated by a technique called electrophoresis, they form a unique pattern that serves as an identity profile.
That pattern can then be compared with the pattern from a criminal suspect's blood--which, in most states, is routinely obtained, with a court order if necessary. The odds that such genetic fingerprints from two individuals will be identical range from one in 200,000 to one in 30 billion, depending on the number of fragments compared.