DNA Detectives

By Jeffrey Kluger

In October a 24-year-old woman who had been comatose for more than three years gave birth to a baby girl. It was only a few days before the delivery that the staff at the woman's nursing home in Lawrence, Mass., even discovered that she was pregnant. Under the circumstances, the pregnancy had to have been the result of rape; yet the woman was uniquely unable to name her assailant. If she couldn't speak, however, the blood of her daughter could. Shortly after the baby's birth, the police drew a sample of the infant's blood, then took voluntary samples from male relatives of the woman as well as from nursing-home personnel and others who might have had access to her. Comparing the men's DNA with the baby's, they figured, could lead them to the rapist.

While the genetic dragnet cast over Lawrence has not yet yielded any arrests, it has led to controversy. Over the past decade, as anybody who followed the O.J. Simpson trial can attest, DNA profiling has become almost as important a part of crime fighting as fingerprinting. But even as technology pushes forensic science forward, the Constitution has worried it back. The Fourth Amendment guarantees citizens protection from unreasonable searches and seizures, and although the Founding Fathers didn't contemplate strands of DNA when drafting the Bill of Rights, what search could be more invasive than an assay of our very genes?

In Lawrence the question is being raised anew, as men--all but one of them presumably innocent--weigh the ease of submitting to a DNA test against their right to refuse and the suspicion that would be raised if they did. It's a problem that is becoming more and more familiar--and, for civil libertarians, cause for more and more alarm. "These are technologies in which powerful organs in society control members with less power," frets Philip Bereano, a member of the American Civil Liberties Union's board of directors. "They are inherently violative of civil rights."

The power of DNA technology expanded exponentially last fall when the FBI activated its new Combined DNA Index System. A database containing the gene prints of 250,000 convicted felons--as well as 4,600 DNA samples left behind at the scene of unsolved crimes--the system acts as a sort of investigatory intranet through which law-enforcement officials can surf when trying to match a known criminal to a crime.

To streamline sampling, the system identifies subjects not by their entire genetic blueprint but by tiny stretches of DNA coding, known as short tandem repeats that are just two to seven base-pairs long. Though little more than genetic gibberish, STRs yield remarkably accurate results. If three of the ministrands match a suspect's, the likelihood is 2,000 to 1 that police have the right person. Nine matches boost the odds to 1 billion to 1. FBI sampling rules require no fewer than 13 matches. "Its success as a crime-fighting tool is incredible," says Christopher Asplen, director of a national DNA-study commission.

Too incredible for some people's taste, however. Once a database like this is assembled, civil rights advocates argue, it is unlikely to be disassembled, and it is only a matter of time before data grow to include not just wrongdoers but also law-abiding citizens. Proponents of DNA testing dismiss this as libertarian alarmism, but experience suggests otherwise.

In December the police commissioner of New York City recommended that anyone even arrested for a crime--never mind convicted of one--be required to submit a routine DNA sample. In England, where a genetic database has operated since 1995, suspects are routinely screened this way--more than 360,000 gene prints are online--though police do promise that such profiles will be scrubbed from the record if the person is cleared. English officials investigating a crime in a small town sometimes perform mass screenings in which thousands of people are asked to surrender a mouth swab full of DNA. The law gives anyone the right to decline, but as residents of Lawrence, Mass., are learning, no law can prevent the slit-eyed look police give a person who actually chooses to exercise that right. "There is no such thing as a technology like this without an ideology of surveillance and control behind it," says Bereano.

The problem for Bereano and other detractors is that DNA technology works. In England as many as 500 matches are made a week between database entries and samples taken from crime scenes. When mass sweeps are conducted, the police claim a 70% success rate in cracking the crime they're investigating. In the U.S., where the months-old national database has barely got on its feet, the FBI claims that 200 outstanding cases have already been solved. What's more, on occasion, DNA sampling benefits not only the people investigating crimes but also the people convicted of them. Since 1976, 75 death-row inmates have been spared execution in the U.S. when their convictions were overturned. At least 10 of the reversals came on the strength of new DNA evidence.

This kind of investigatory yin and yang is keeping opponents of DNA fingerprinting mollified--but for how long? Now that the gene genie is out of the bottle, there may be little that can be done to stuff it back in. Scientists in the U.S. and England already speak dreamily of moving beyond testing STRs alone, expanding their work to sample other--more richly encoded--areas of the genome. Kevin Sullivan of England's Forensic Science Service predicts that within a decade researchers may be able to use DNA analysis to draw a sort of genetic police sketch of a suspect's appearance, including build, race, facial shape and even inherited physical defects.

The most complex traits, of course, would be the ones even the best detectives would have a hard time seeing: personality traits. If temperament is at least partly determined by genetic hard-wiring, somewhere in the vast tangle of human DNA there must be strands that influence behavior--including criminal behavior.

The problem is, If you could locate such genes, what would you do with that knowledge? Should you incarcerate people for crimes they haven't yet committed but are genetically predisposed to commit? Is it possible to fix such miswired genes, and if so, should you try? The possibility of mucking about with such fundamental genetic coding gives a lot of people existential shivers--and it should. "This is the kind of technology that would flourish in an Orwellian society," says Bereano.

For now there's nothing to suggest that things are nearly so dire: DNA fingerprinting has been used for years, and so far it is only wrongdoers who have real cause to wish it hadn't. But when it comes to scientific advances, human beings have often been a slapdash species--racing out ahead with a new technology before fully appreciating its power. If DNA fingerprinting should get into the wrong hands, society's law-abiding members may find they have more in common with its lawbreakers than they ever dreamed possible.

--Reported by Melissa August/Washington and Helen Gibson/London

With reporting by Melissa August/Washington and Helen Gibson/London