The Gene Police
In Britain, Controversial DNA-Tracing Tactics Are
Helping Forensics Experts Crack Unsolved Crimes
By GAUTAM NAIK
February 23, 2008
Birmingham, England
In April 1993, a man in a balaclava mask escaped after sexually assaulting a 36-year-old woman in the town of Bridgwater, England. More than 13 years later, forensic detectives used an unusual approach to track the man down: A genetic trace that led first to his sister.
Known as familial searching, the U.K. technique has already helped crack 20 difficult cases and led to the arrest of several long-elusive murderers and rapists.
The innovation is propelled by the growth of Britain's DNA database, which holds the records of 4.2 million people in England and Wales, or nearly 8% of the population there, one of the largest proportions in the world. Anyone arrested -- including for minor offenses -- must provide a DNA sample, which stays in the database permanently, even if the person is acquitted. About a quarter of the profiles are of minors, some as young as 10.
The U.S. is now considering following Britain's lead. The Federal Bureau of Investigation's national DNA database, plus those maintained by individual states, together hold about 5.6 million DNA profiles, or almost 2% of the population. The overwhelming majority of all profiles are from convicted felons.
But 11 states have passed laws to allow DNA samples to be taken from people who have been arrested but may not have been convicted. The Department of Justice separately is finalizing rules permitting genetic profiles to be collected from anyone arrested by federal authorities. And in March, the FBI will host a symposium to discuss the merits of familial searching. One speaker is Tony Lake, chairman of the U.K.'s national DNA board.
Familial searching has very rarely been used in the U.S. because crime labs typically don't have the sophisticated software needed for such searches. Nor do U.S. database administrators yet have the explicit legal authority to use the approach. "We're promoting a public debate, but we have taken no position yet on familial searching," says Thomas Callaghan, head of the FBI's DNA database program.
In a standard investigation using DNA, experts take a sample obtained from a crime scene and try to identify the culprit by matching the sample with DNA profiles already stored in a database from previous crimes. A familial search looks for a near match, rather than an identical match. A near match may indicate that the sample in the database is that of a close blood relative, who can then help lead police to the actual perpetrator.
"DNA is the best kind of forensic evidence there is -- it's better than an eyewitness account," says Philip Reilly, a U.S. geneticist, attorney and expert on DNA forensics. "So there's been a drumbeat to increase the scope of the laws on both sides of the Atlantic."
Profiling the Innocent
Civil-liberties groups oppose the rapid expansion of DNA databases, arguing that they risk placing sensitive personal information in the hands of the government. Unlike old-fashioned fingerprints, they say, DNA contains health and hereditary data such as paternity markers that could be misused. Leaked data, for example, could be used to deny insurance coverage or employment to people identified as being at risk for a genetic disease.
Forensic experts say such fears are overblown because databases hold only a tiny fraction of a person's DNA makeup. The information is stored as a series of numbers converted from a physical DNA sample.
Critics also say some research techniques pose ethical problems. They say a DNA-based "ethnic inference" test can provide uncertain predictions about the race of potential suspects that may mislead the police or reinforce existing prejudices. Pioneered by British forensic experts, the test tries to identify whether the subject belongs to one of five racial groups, such as "white-skinned European" or "Indian subcontinent." A separate DNA test can identify criminals with red hair.
British geneticist Alec Jeffreys, who invented the technique of genetic profiling in 1984, has questioned the need to retain DNA profiles of innocent people. He says the DNA database was originally set up only for convicted criminals who could be quickly identified if they committed additional crimes. In January, the U.K. government's Human Genetics Commission launched a public inquiry into the practice of storing DNA from people who are acquitted or never charged.
The Home Office, which oversees the police forces of England and Wales and their combined DNA database, say those who are innocent have nothing to fear from providing a sample. They say retaining this evidence is no different from recording other forms of information such as photographs and witness statements.
In 1995, the U.K. became one of the first places to set up a national DNA database to fight crime. The database does not include profiles from Scotland or Northern Ireland, which have separate systems. Police were initially required to destroy DNA samples and profiles if a suspect's charges were dropped or if the person was acquitted. But that requirement was eliminated in 2001. Three years later, police were allowed to take DNA from anyone they arrested.
Now, U.K. police are seeking powers to let them take DNA samples from people who are charged with minor infractions like speeding or littering. They hope to obtain these samples via cheek swabs done on the street, an approach similar to a breathalyzer test. A senior appellate judge, as well as former prime minister Tony Blair, have called for the database to ultimately include DNA profiles of every U.K. resident.
Reopening the 'Nora' Case
Familial searching has netted several notable successes for British police. It was first used in 2003, when a driver was killed from a brick flung at his truck. DNA scraped from the brick led investigators to a relative of the assailant. The brick thrower was convicted of manslaughter.
In the early 1980s, a man assaulted four women in the county of Yorkshire. He was dubbed the "Shoe Rapist" because he made off with his victims' footwear. Two decades later, police sorted through 43 familial matches to his DNA, including a woman once arrested for drunk driving. When the police questioned her brother, a respected businessman, he confessed and was sentenced to 15 years. Investigators found dozens of stilettos hidden at his home and workplace.
One of the most recent breakthroughs in familial searching occurred in the case of the 36-year-old woman raped in Bridgwater on April 26, 1993. British laws prohibit the publication of the victim's real name; in police files she is referred to simply as "Nora."
That night, as Nora walked along a canal to her sister's home, she was grabbed by a man in a balaclava mask, dragged into the undergrowth and sexually assaulted. Nora later told police that the man had a local accent, and that the skin around his eyes was white. Because of similar attacks in recent months, police figured they were looking for a serial rapist.
A DNA sample obtained from the assailant's semen was first checked against genetic profiles of known criminals in the national database. There were no matches. The police then began a massive manhunt.
They set up an "incident room," conducted house-to-house inquires, and assigned up to 30 staff to investigate the rapes. They tried to match the DNA from 20 local men with previous sexual-assault convictions, but came up with nothing. After months of fruitless police work, the investigation was scaled down and eventually shelved.
By 2003, speedy computers and new methods, such as familial searching, persuaded police forces across Britain to re-investigate tens of thousands of unsolved rapes and murders committed decades earlier. That year, police in Bristol, a large city 40 miles from Bridgwater, set up a six-person group for their own backlog of "cold case" crimes.
The team considered 1,100 rape cases, going back to 1976 and used various criteria to narrow the list. They eventually sent a dozen DNA samples to the Forensic Science Service, a government-run outfit in the city of Birmingham that analyzes DNA and develops new forensic technology. The samples sent from Bristol came from the most notorious cases -- including the Bridgwater rapes -- and were sent for familial searching and other sophisticated tests.
Familial searching is based on the way we inherit genes. Every gene comes from either one's father or mother. Close blood relatives -- parents and their children, or siblings -- will share alleles, which are versions of a particular gene. Because alleles can be used as genetic markers, DNA profiles from a crime scene can be compared to profiles of known individuals to see if there are any close family matches.
In doing a standard genetic match, U.K. scientists look at 20 alleles along a string of DNA. If a match is found for all 20 alleles for a pair of DNA profiles, there's virtually no doubt that both DNA samples come from the same person -- unless the samples come from identical twins. Near matches of only 17, 18 or 19 alleles may indicate a close blood relative.
A Request For a Family Tree
In late 2005, the FSS ran a familial search of the Bridgwater rapist's genetic profile against all DNA fingerprints stored in the national database. That generated a list of 4,000 people with close matches, each a potential parent, child, or sibling of the offender.
Based on Nora's description, police knew they were looking for a white man with a strong local accent. So they eliminated all non-whites on the list. They also excluded people who weren't from the local area, the counties of Avon and Somerset.
Around this time, detectives re-visited Nora, informing her that they were taking another look at her case, using familial searching. "She immediately became upset and tearful at the mention of the re-investigation" as it brought back bitter memories from a dozen years earlier, says Michael Britton, the detective-sergeant in charge of the case. But Nora agreed to support a prosecution if the man was ever identified.
Of the remaining names, Mr. Britton and his colleagues next focused on the 100 or so local males. To narrow down a possible family link, the Bristol police asked the FSS to do a Y-STR comparison.
Y-STRs are repeated chemical sequences along DNA that are found only on the male Y chromosome. The sequences are inherited along the paternal line and change little over generations. By comparing the Y-STRs from the Bridgwater attacker to the Y-STRs of the 100 males on the list, the police hoped to identify a male relative -- such as the father or a brother -- of the offender.
Yet again, there were no matches. By September 2006, the investigation was petering out. The last prospects on the list were seven females whose DNA pointed to a possible kinship with the perpetrator. Mr. Britton and his colleagues visited them and obtained their family trees, in the hope of pinpointing male relatives.
It was a sensitive request. "Some got alarmed," remembers Mr. Britton. "They said: 'Are you suggesting that one of my relatives is a rapist?' "
Lifetime of Genetic Surveillance
This is the very issue that alarms critics of familial searching, who note that the technique focuses an investigation on the innocent relatives of a criminal -- or people who may not be related to the culprit at all.
In June 2006, Frederick Bieber, associate professor of pathology at Harvard Medical School, and two colleagues published a study in the journal Science on the potential use of familial searching in the U.S. They concluded that the technique would increase the chances of finding a criminal by 40% when compared with current methods of DNA matching.
But they also warned that the method "could raise new legal challenges, as a new category of people effectively would be placed under lifetime genetic surveillance."
The family trees in the Bridgwater case yielded four male names, including Geoffrey Godfrey, a construction worker who lived a few streets from the scene of the 1993 Bridgwater rapes. Mr. Godfrey was listed on the tree given to police by his sister, who was in the national DNA database because she had once given a DNA sample after a minor driving-related offence.
Born in 1965, Mr. Godfrey roughly matched the age of Nora's assailant. On Sept. 13 and 20, police tried him at home and got no answer. When they knocked on his door the following Saturday, he was in bed with a cold.
The police told Mr. Godfrey that they were looking into sexual-assault cases and wanted to eliminate people on a list. But they kept the details vague, and didn't disclose that the crimes they were investigating were a dozen years old. Mr. Godfrey, who had recently married, willingly provided a cheek swab.
Mr. Britton sent the swab to the FSS, in order to compare Mr. Godfrey's DNA profile against that of the Bridgwater attacker. Two days later, the FSS experts faxed the result: It was a perfect match.
Mr. Godfrey was charged with four sexual assaults in Bridgwater. He recently pleaded guilty to the attack on Nora, and is now serving a six-year sentence. The court ordered the other three charges to be dropped because of insufficient proof.
"He is deeply ashamed of what happened," says Ian Pringle, the barrister who defended Mr. Godfrey. "It was a long time ago."
For Nora, the process has dredged up painful memories. In response to questions relayed to her via Mr. Britton, Nora says she is disappointed at the length of her assailant's sentence. But at the same time, she adds, the guilty plea saved her the "tremendous ordeal" of having to testify, and thereby re-live in court the horror of the attack on her.
Write to Gautam Naik at
[email protected]
http://online.wsj.com/article_email/SB120372569853187081-lMyQjAxMDI4MDIzMzcyMjM1Wj.html
