The man who pumped bullets into the heads of two Annapolis lawyers in 1994 was careful to leave no witnesses, no weapon, and no fingerprints. He was thirsty, though. And that was what eventually did him in.
The streak of saliva Scotland E. Williams left behind after taking a swig from a water glass sitting on a kitchen counter betrayed him. On the glass was enough of his DNA for police to put him at the crime scene, and Williams was convicted of the double-murder last spring.
These days, it doesn't take much to thwart what might have been the perfect murder only 10 years ago. Just a drop of saliva, a spot of blood or a couple of strands of hair and there it is, all that is unique to you, bathing in the light of a microscope.
DNA testing has the potential to make a liar out of the president of the United States. To expose a mix-up of newborns at a Virginia hospital three years ago. To give a name to remains in the Tomb of the Unknown Soldier.
This decade-old forensic science is leaving its own mark on the culture. Some welcome it as the best crime-fighting technique since the fingerprint match. Others curse it, calling it a black art and statistical voodoo that, if used nefariously, could undermine each individual's right to privacy.
"People are fascinated, terrified, appalled and befuddled when it comes to genetics and DNA testing," says Arthur Caplan, director for the Center for Bioethics at the University of Pennsylvania. "Finding out that scientists are testing our DNA takes away some certainty that our identity is inviolate, secret."
As the nation waits for the FBI to reveal whether President Clinton may have left evidence of his DNA on Monica Lewinky's dress, perhaps proving a sexual relationship, debates over the ethical and scientific uses of genetic testing have been reignited.
Not since the O.J. Simpson murder trial and its infamous bloody glove and socks have people been so preoccupied with DNA testing.
"It makes me nervous," says Diane Silverstein, a Baltimore County juror who voted to convict a man for murder after police found his saliva on a cigarette butt near the victim's body. "I feel like I am a slave to some lab technician. If he does something wrong, looks at something askance, I could be pinned for a murder or anything else."
Silverstein, 47, isn't given to believe in conspiracy theories, she says. But even after her court experience, she doesn't understand just how DNA testing works. It's too "sci-fi," she says, and that makes her suspicious.
"Just how far will it all go? What do I do if I'm mugged? Snatch a strand of hair from his beard and trot down to the police station and tell them, 'This is the guy you want. Now go get him?' "
Not quite, but maybe some day soon.
Much is still misunderstood about how conclusively DNA testing can point a definitive finger at suspect.
"It is not perfect," says Michael Baird, vice president of laboratory operations at Lifecodes Corp., a pioneer biotechnology company that specializes in DNA testing. "It's not as good as a fingerprint."
The odds
So far, DNA testing is an odds-maker. It can't say definitively that two samples match. Instead it offers odds that two samples have a good chance of being from the same source. Of course, in some cases, the odds that the science is wrong are astronomical. A one-in-a-million chance that two samples don't match is a long shot indeed, but there is always that tiny chance looming.
Many things have to go right before a DNA test can be used. Hair has to contain the root or it is useless. Blood and other bodily fluid samples can be ruined if they are mixed with blood and fluids from another source. A sample can be too small to measure.
But DNA testing also isn't as delicate as many think.
Pathologists and scientists are amazingly adept in re-creating a person's DNA blueprint. Blood, even if dried or old, is still an excellent sample. The same goes for semen and saliva. Hairs are almost always present when two people come in contact. The minute samples of DNA are then cloned and built into a profile.
So, theoretically, could Clinton's DNA still be found on Lewinsky's dress, even if the dress had been dry cleaned?
Absolutely, say DNA experts. It depends on what chemicals were used in the cleaning process. There could still be enough DNA present to suggest that he and the White House intern had sexual contact.
"You can try to blow up your evidence, or wash it away, or dispose of a victim's body, or just pray that nothing will ever be found," says David L. Brody, chief or the Boston Police Department Crime Lab Unit. "But we'll still find or reconstruct virtually anything to a microscopic degree."
The champions of DNA testing are most always scientists and law enforcement agencies. But DNA testing is used in more than just criminal cases.
Scientists have used DNA testing to solve decades-old mysteries based on a single shred of bone, hair or tissue. DNA testing was used to identify the bones of Russia's Czar Nicholas II and his family, murdered by a Bolshevik secret police squad in 1908. It also was used to prove that the body in Jesse James' grave was indeed that of the notorious outlaw.
Today, DNA testing is most often used in paternity cases. It can exclude someone believed to be the father with 99.97 percent certainty. The recent Virginia baby-switching case that revealed two families had taken home the wrong newborns began with a father's suspicion and a DNA test.
Last year alone, 173,000 paternity tests were done by labs accredited by the American Association of Blood Banks, more than double the 77,000 in 1988. More than 51 labs nationwide, including two in Maryland, are conducting the tests.
"At a time when the divorce rates are climbing and everyone is having a baby out of wedlock, more fathers and mothers want to know for sure," says Christine Mason O'Connell, a pediatric nurse in Washington. "I don't have a problem with using DNA testing for that.
"But when you use it for tracking people and storing all of our information in a computer chip, I have big problems with that. Everyone is guilty until they are proved innocent. That is not how our legal system should work."
People's fears
It is such "Big Brother is watching" concerns that get people riled up so unnecessarily, says Paul Mones, an attorney and author of "Stalking Justice," a true story of a Virginia man executed in 1994 solely on the basis of DNA evidence.
"I don't think there is anything to be afraid of," Mones says. "If I were guilty of a crime, the last thing I would want is a DNA test. But if I knew I was innocent, it would be the first thing I would want."
Mones suspects that people are afraid primarily because DNA testing is a relatively new science.
"I think people were afraid of electricity at one time," he says. "The Big Brother concerns are much more theory than practice."
In all states except Vermont and Rhode Island, DNA data banks have been established to store genetic material information from felons. That information is being used to match samples taken from recent crime scenes in the quest for elusive criminals.
The Federal Bureau of Investigation is working on a pilot program that will link states' DNA information into a central data bank, creating a web that could help track down felons no matter where they commit their crimes.
So far, few felons have been caught using data banks. Creating a profile is a slow process, taking up to six weeks to complete. Consequently, most states have a backlog of cases.
In the United Kingdom, there is a push by law enforcement agencies to register everyone, not just felons, into a DNA data bank.
"I'd lead a revolt if that happened here in this country," says Elaine Singletary, a substitute teacher for Howard County, who says she became interested in the power of DNA testing during the Simpson trial three years ago.
"I learned that too much can happen to pervert the system," she complains.
Scientists admit that people are quicker to believe that the DNA testing procedure is vulnerable to outside factors. But, they say, scientists are neutral. They don't have any reason to alter the outcome of tests.
The fact of DNA testing, though, has invaded our culture so thoroughly that many people think they understand more about it than they really do. Movies, television shows and books have both educated and misrepresented the power of forensic science.
Who doesn't know that when you handle explosives, residues will remain on your skin or that microscopic fibers can be swapped when your clothes touch someone else's? Now pop culture is tackling the sexier aspects of DNA testing with the same fervency. But with pop-culture intellect come misperceptions, scientists and law enforcement officers say. Juries don't always comprehend the scope and power of DNA testing.
In the Scotland Williams case, prosecutors spent more than a week on testimony from experts explaining the process. But things can still be muddled by how the testimony is presented.
Jonathan Koehler, a criminologist at the University of Texas at Austin, cites a study in which juries were presented with the same information about the probability of a DNA match, only in different ways.
On one jury, told that the probability was 0.1 percent, 75 percent of the jurors thought the accused was likely to be guilty. On another jury, when the same probability was explained in terms of "one in a thousand," fewer than half thought he was guilty.
While the debate continues, the power and the scope of DNA testing is growing. Scientists will soon be able to identify DNA from a single cell. The DNA from minute pieces of evidence, such as a speck of dandruff or a single sperm, will be amplified until an individual can be identified.
Also, scientists predict that they soon will be able to determine almost an exact physical description from strands of DNA. Race, hair texture, eye color, even the shape of a nose can be figured out.
L "We are coming closer and closer to perfection," says Baird.
Pub Date: 8/13/98