Crime labs finding questionable DNA matches FBI tries to keep national database away from lawyers

Thomas Callaghan has opposed Arizona-style searches. Illustrates DNA (category a) by Jason Felch and Maura Dolan (c) 2008, Los Angeles Times. Moved Monday, July 28, 2008. (MUST CREDIT: Photo courtesy of the FBI.) less Thomas Callaghan has opposed Arizona-style searches. Illustrates DNA (category a) by Jason Felch and Maura Dolan (c) 2008, Los Angeles Times. Moved Monday, July 28, 2008. (MUST CREDIT: Photo courtesy of the ... more Photo: FBI, TPN Photo: FBI, TPN Image 1 of / 3 Caption Close Crime labs finding questionable DNA matches 1 / 3 Back to Gallery

In 2001, Arizona crime laboratory analyst Kathryn Troyer was running tests on the state's DNA database when she stumbled across two felons with remarkably similar genetic profiles.

The men matched at nine of the 13 locations on chromosomes, or loci, commonly used to distinguish people.

The FBI estimated the odds of unrelated people sharing those genetic markers to be 1 in 113 billion. But the mug shots of the two felons suggested that they were not related: One was black, the other white.

In the years after her discovery, Troyer found dozens of similar matches - each defying impossible odds.

As word spread, Troyer's findings raised questions about the accuracy of the FBI's DNA statistics and ignited a legal fight over whether the nation's genetic databases ought to be opened to wider scrutiny.

The laboratory of the Federal Bureau of Investigation, which administers the national DNA database, tried to stop distribution of Troyer's results and began to block similar searches elsewhere, even those ordered by courts, according to an investigation by the Los Angeles Times.

At stake is the credibility of the compelling odds often cited in DNA cases, which suggests an all-but-certain link between a suspect and a crime scene. When DNA from blood or skin cells matches a suspect's genetic profile, it can seal the suspect's fate with a jury, even in the absence of other evidence. As questions arise about the reliability of ballistic, bite-mark and fingerprint analysis, genetic evidence has emerged as the forensic gold standard.

But DNA "matches" are not always what they appear to be. Although a person's genetic makeup is unique, his "genetic profile" - a sliver of the full genome - may not be. Siblings often share genetic markers, and unrelated people can share some by coincidence.

No one knows how rare DNA profiles are. The odds presented in court are best estimates from the FBI.

The Arizona search was a first test of those estimates in a large state database, and the results were surprising.

Defense attorneys seized on the Arizona discoveries as evidence that genetic profiles match more often than statistics imply and are not unique.

Now, lawyers around the country are asking for searches of their own state databases. Scientists and legal experts want to test the accuracy of statistics using the nearly 6 million profiles in the Combined DNA Index System (CODIS), the national network that includes state and local databases.

"DNA is terrific and nobody doubts it, but because it is so powerful, any chinks in its armor ought to be made as salient and clear as possible so jurors will not be overwhelmed by the seeming certainty of it," said David Faigman, a professor at the UC's Hastings College of the Law who specializes in scientific evidence.

FBI officials argue that the use of CODIS is limited to criminal justice agencies. Defense attorneys are allowed access to information about specific cases, not the databases in general. Bureau officials say critics have exaggerated or misunderstood Troyer's discoveries.

Indeed, experts agree that many - but not all - of the Arizona matches were to be expected statistically because of the unusual way Troyer searched for them.

In a typical criminal case, investigators look for matches to a specific profile. But Troyer looked for any matches among all the thousands of profiles in the database, greatly increasing the odds of finding them.

As a result, Thomas Callaghan, head of the FBI's CODIS unit, has dismissed Troyer's findings as misleading and meaningless.

Callaghan urged authorities in several states to object to "Arizona searches," as they came to be known, advising them that the probes could violate the privacy of convicted offenders, tie up databases and lead the FBI to expel offending states from CODIS - a penalty that could seriously hamper states' ability to solve crimes.

The FBI's arguments have persuaded courts in several states to block the searches. But in two states, judges overruled the objections. The resulting searches found nearly 1,000 more pairs that matched at nine or more loci.

"I can appreciate why the FBI is worried about this," said David Kaye, an expert on science and the law at Arizona State University and former member of a national committee that studied forensic DNA.

But "people's lives do ride on this evidence," he said. "It has got to be explained."

After her discovery, Troyer and colleagues in the Arizona Department of Public Safety's Phoenix DNA lab were intrigued.

At the time, states looked at nine or fewer loci when searching for suspects. (States now compare 13 loci, though often fewer are available from old or contaminated crime scene evidence.) Based on Troyer's results, colleagues believed that a nine-locus match could point investigators to the wrong person.

"If you're going to search at nine loci, you need to be aware of what it means," said Todd Griffith, director of the Phoenix lab. "It's not necessarily absolutely the guy."

Troyer made a poster for a national conference of DNA analysts. It showed photos of the white man and the younger black man next to their remarkably similar genetic profiles. Some conferees had seen similar matches in their own labs.

Three years later, Bicka Barlow, a San Francisco defense attorney, came across Troyer's poster information on the Internet as she prepared to defend a client accused of a 20-year-old rape and murder.

A database search had found a nine-locus match between her client's DNA profile and semen found in the victim's body. Based on FBI estimates, the odds of a coincidental match were 1 in 108 trillion.

Barlow wondered if there might be similar coincidental matches in California's database - the world's third-largest, with 360,000 DNA profiles. She called Troyer.

Barlow learned that Troyer had searched the growing Arizona database and found more pairs of profiles matching at nine and even 10 loci.

Encouraged, Barlow subpoenaed a new search of the Arizona database. Among about 65,000 felons were 122 pairs that matched at nine of 13 loci. Twenty pairs matched at 10 loci. One matched at 11 and one at 12, though both belonged to relatives.

Barlow was stunned. Such matches were almost unheard of.

After Barlow received the search results, Callaghan reprimanded Troyer's lab in Phoenix, saying it should have sought FBI permission before complying with the court order.

Asked later whether Callaghan had threatened her lab, Troyer testified, "I wouldn't say it's been threatened, but we have been reminded."

Dwight Adams, then director of the FBI lab, faxed a letter to Griffith, Troyer's supervisor, saying the lab was "under review" for releasing search results.

Arizona officials obtained a court order to prevent Barlow from sharing the results. But it was too late. Barlow had e-mailed the results to colleagues and DNA experts around the country. Soon, defense lawyers in other states were seeking "Arizona searches."

In January 2006, not long after Barlow distributed the results of the court-ordered search in Arizona, the FBI sent out a nationwide alert to crime labs warning of similar defense requests.

Soon after, the bureau's arguments against Arizona searches were being made in courtrooms around the country.

In California, Michael Chamberlain, a state Department of Justice official, persuaded judges that such a search could have "dire consequences" - violating the privacy of convicted offenders, shutting down the database and risking the state's expulsion from the DNA system.

When similar arguments were made in an Arizona case, the judge ruled that the search would be "nothing more than an interesting deep sea fishing expedition."

But in Illinois and Maryland, courts ordered the searches to proceed, despite opposition from the FBI and state officials.

In July 2006, after Chicago-area defense attorneys sought a database search on behalf of a murder suspect, Callaghan held a telephone conference with Illinois crime lab officials.

The topic was "how to fight this," according to lab officials' summary of the conversation, which became part of the court record.

Callaghan suggested they tell the judge that Illinois could be disconnected from the database system, the summary shows. Callaghan then told lab officials that "it would in fact be unlikely that IL would be disconnected," according to the summary.

"I didn't say it was unlikely to happen," Callaghan said in an interview. "I was asked specifically, what's the likelihood here? I said, I don't know, but it takes a lot for a state to be cut off from the national database."

A week later, the judge ordered the search. Lawyers for the lab then took the matter to the Illinois Supreme Court, arguing in part that Illinois could lose access to the federal database. The court refused to block the search.

The result: 903 pairs of profiles matching at nine or more loci in a database of about 220,000.

State officials obtained a court order to prevent distribution of the results. The Times obtained them from a scientist who works closely with the FBI.

A similar fight occurred in a death penalty case in Maryland during the summer and fall of 2006.

The prosecutor saw a DNA match between a baseball cap at the crime scene and the suspect as so definitive that he didn't plan to tell the jury about the chance of a coincidental match, records show.

Seeking to cast doubt on the evidence, the defense persuaded the judge to order an "Arizona search" of the Maryland database. The state did not comply.

After the defense filed a contempt-of-court motion, Michelle Groves, the state's DNA administrator, argued in court and in an affidavit that, based on conversations with Callaghan, she believed the request was burdensome and possibly illegal.

According to Groves, Callaghan had told her that complying with the court order could lead Maryland to be disconnected from CODIS - a result Groves' lawyer said would be catastrophic.

Groves' affidavit was edited by FBI officials and the technology contractor that designed CODIS, court records show.

Before submitting the affidavit, Groves wrote the group an e-mail saying, "Let's see if this will work," court records show.

It didn't.

After Judge Steven Platt rejected her arguments, Groves returned to court, saying the search was too risky. FBI officials had now warned her that it could corrupt the entire state database, something they would not help fix, she said.

Platt reaffirmed his earlier order, decrying Callaghan's "unilateral" decision to block the search.

"The court will not accept the notion that the extent of a person's due process rights hinges solely on whether some employee of the FBI chooses to authorize the use of the (database) software," Platt wrote.

The search went ahead in January 2007. The system did not go down, nor was Maryland expelled from the system.

In a database of fewer than 30,000 profiles, 32 pairs matched at nine or more loci. Three of those pairs were identical at 13 out of 13 loci.

Experts say they most likely are duplicates or belong to identical twins or brothers. It's also possible that one of the matches is between unrelated people - defying odds of 1 in 1 quadrillion.

Maryland officials never did the research to find out.