ACCURACY OF NEW DNA TEST IS CALLED INTO QUESTION

by Laurie P. Cohen


The FBI has a powerful new weapon that gets its man nearly every time it is deployed. One catch: In some cases, the weapon may demolish the innocent along with the guilty. Another catch: Defendants can use it, too.

The weapon, called mitochondrial DNA testing, is a new way to analyze crime-scene evidence. An important step beyond standard DNA testing, it has been used by the Federal Bureau of Investigation only since August 1996 and has resulted in six convictions in six attempts.

It will be tried by a defendant for the first time in the long-running saga of Jeffrey MacDonald, the former Army surgeon who was convicted in 1979 of killing his wife and two daughters but who has always insisted a marauding band of drug-crazed hippies did the deed instead. If he is right, mitochondrial DNA testing of strands of hair found under his daughters’ fingernails, and preserved all these years, might yet show that he was not the killer.

Though most people outside of scientific circles have never heard of mitochondrial DNA, it has been used to identify Czar Nicholas II’s bones and to prove that the body in Jesse James’s grave is truly that of the outlaw. Since 1991, the military has also employed it to identify soldiers’ remains.

Realm of the Living

The FBI crime lab is responsible for moving the technique into the realm of the living, despite scientific concerns about the accuracy of the method. Thanks to the FBI, mitochondrial DNA testing has already occurred in about 70 cases that haven’t yet reached trial.

These days, viewers of Court TV know just about as much as the average biology student about DNA, or deoxyribonucleic acid, which contains a person’s unique genetic code within the nucleus of each body cell. With the exception of identical twins, no two individuals share the same genetic code-making ordinary "nuclear" DNA testing a popular means of identification in court cases.

Since 1988, when nuclear DNA testing was first used by the FBI in criminal trials, it has played a part in more than 30,000 cases nationwide. Next year alone, the FBI predicts, it will employ the method in as many as 2,500 cases.

Nonetheless, nuclear DNA testing suffers from a major limitation: It can’t be used unless the evidence is fresh and in good shape; crucially, there have to be cell nuclei present, and hair that has been pulled away from its roots doesn’t contain any nuclei.

Whole New Worlds

In contrast, mitochondrial DNA is located outside of a cell’s nucleus and is much more plentiful than nuclear DNA. Indeed, a single cell will have hundreds, even thousands, of mitochondria, tiny particles that are responsible for converting food to usable energy. That means more DNA can be extracted from smaller, older and less-well-preserved fragments of evidence.

The distinction opens up whole new worlds for prosecutors, who sometimes have nothing more to work with than a strand or two of hair or old skeletal remains. The FBI lab’s small mitochondrial DNA unit in Washington, which employs just two examiners and focuses on hair analysis, is now gearing up to meet rising demand. "We have calls coming in daily from prosecutors," says Joseph DiZinno, chief of the unit.

In the scientific community, though, the much-sought-after forensic tool is being greeted with skepticism. While juries may assume one type of DNA is the same as another, the truth is that mitochondrial DNA—which is inherited from the mother’s side only—doesn’t provide the same kind of unique fingerprint as nuclear DNA. The same mitochondrial DNA sequence is shared by siblings and their mother and all of a person’s maternal relatives for many generations. And a 1993 British study found that even among unrelated people, four out of 100 who were tested shared the same mitochondrial DNA sequence.

Reliability Concerns

So even if a defendant is linked to crime-scene evidence through mitochondrial DNA, there is a small but realistic possibility that he or
she had nothing to do with the crime. "The FBI is bringing mitochondrial DNA into the courtroom and painting it with the same reliability as other DNA typing," says one critic, William Shields, a biologist at the State University of New York in Syracuse. But, he adds, "It isn’t as unique to an individual as nuclear DNA."

Says Edward Blake, a DNA expert with Forensic Science Associates in Richmond, Calif.: "We don’t know enough about mitochondrial DNA in hair to be giving scientific testimony about it." That’s also the view of the nation’s largest private DNA lab, Cellmark Diagnostics Inc., in Germantown, Md. A company spokesman says further study is needed before the lab will begin doing mitochondrial DNA analysis on hair in criminal cases.

Such resistance doesn’t faze the FBI’s Dr. DiZinno. "We wouldn’t have gone on-line if were weren’t confident this was a reliable technique," he says. Dr. DiZinno and Mark Wilson, both former FBI hair examiners, began researching mitochondrial DNA in 1992. By August 1996, they were ready to unveil it in a Chattanooga, Tenn., courtroom. There, the technique helped win the conviction of rape-and-murder defendant Paul Ware in a tangled case in which much of the other prosecution evidence was weak.

The government was fortunate to be able to use Tennessee as its proving ground for mitochondrial DNA testing. Tennessee is one of only six states in which defendants aren’t entitled to pretrial hearings before DNA evidence is admitted. In most states, such a hearing would have subjected the FBI to tough questioning by defense lawyers and the judge regarding scientific procedures and validity. Only then would the judge have ruled on whether the evidence could be heard by a jury. But in Tennessee, a state statute passed in 1991, before anyone involved had heard of mitochondrial DNA testing, decreed that DNA test results are always admissible in court.

FBI Is Prevailing

In a legal system built on precedent, the successful application of the technique in Tennessee was later used by the government as a wedge to help it get mitochondrial DNA testing approved in states in which pretrial hearings are required. "The FBI was happy to legitimize mitochondrial DNA analysis in this state," says Barry Steelman, a state prosecutor who worked on the Ware case, though Dr. DiZinno says the FBI didn’t have any control over where the first case would be tried.

Since the Ware case, even when the defense has presented experts to oppose mitochondrial DNA evidence, the FBI has prevailed.
Early this year, the FBI’s mitochondrial tests linked a former police officer to the 1993 murder of a man in Boone, N.C. After years of delay, defense lawyer Bruce Kaplan says that mitochondrial testing produced "the only physical evidence" linking the defendant to the crime.

Mr. Kaplan says use of the test wasn’t a close call for the judge, even though the defense argued that the method wasn’t scientifically sound. "The FBI comes in and testifies that mitochondrial DNA has been previously admitted elsewhere and is accepted in scientific circles, and that was that," Mr. Kaplan says.

Prosecutors have also been helped by the fact that not every defense lawyer has attempted to challenge the method. "I didn’t think I was going to win an admissibility hearing, so I didn’t ask for one," says Fred Brown, the defense lawyer in a Waco, Texas, case in which a defendant was accused of mailing a bomb to his estranged wife. Postconviction appeals in these cases, objecting to the use of mitochondrial DNA testing, haven’t yet been heard by appellate courts.

In explaining their new forensic weapon to juries, FBI agents DiZinno and Wilson won’t say that mitochondrial DNA can be used to make a positive identification. Instead, they speak of the frequency that a particular DNA sequence appears in its current database of 1,043 individuals. (Sandy Zabell, a Northwestern University math professor, has argued in court, so far unsuccessfully, that the FBI’s database is too small and too narrowly drawn to lead to any conclusion at all.)

Jurors Are Confused

By contrast, in standard DNA cases, FBI agents give jurors statistics indicating the likelihood that a defendant’s DNA could have come from another person. That likelihood is usually very small, on the order of one in 200 billion.

Nonetheless, the distinctions between nuclear and mitochondrial DNA appear to be lost on many jurors. Indeed, the six jurors in mitochondrial DNA cases who were interviewed for this article spoke—incorrectly— of mitochondrial DNA’s powerful capacity to identify suspects.

"Is there a difference between kinds of DNA?" asks Linda Hicks, a juror in the North Carolina case. "All I can say is the DNA showed it pretty well matched" the defendant. Says Phillip Summerlin, a hospital chaplain who was a juror in the Ware case, "I thought mitochondrial DNA was a good way of identifying people." Hank Hill, the lawyer for Mr. Ware, says jurors in DNA cases have been heavily influenced by the O.J. Simpson case, which involved standard nuclear DNA testing rather than mitochondrial testing. He says they now tend to be uncritical of all DNA evidence because they believe Mr. Simpson was wrongly acquitted. "After O.J., most of middle-class America, which is where juries come from, figure, ‘If you’ve got DNA, you have to convict,’ " Mr. Hill says. "They don’t distinguish between this DNA and that. It’s all DNA to them."

‘Fatal Vision’ Case

What hurts most criminal defendants, though, may be the only thing left that can help Dr. MacDonald, who was the subject of the Joe McGinniss book "Fatal Vision" and the made-for-TV movie that followed. He has a chance to prove his innocence, after being shut down in one appeal after another, because the government itself threw open the door to a technique that courts otherwise might not have approved.

Since his conviction, Dr. MacDonald’s lawyers had repeatedly tried and failed to get courts to give Dr. MacDonald a new trial. The odds of getting any court to listen were growing more difficult with time; U.S. Supreme Court rulings in recent years had made it all but impossible for prisoners who have been through the appeals process once to have their cases reopened. But last April, the much-publicized troubles at the FBI Laboratory gave Dr. MacDonald a fresh opening to try again.

Dr. MacDonald had always claimed that the intruders who had killed his family were led by a woman wearing dark clothing, a floppy hat and a long, blond wig. His lawyers tried to reopen the case in 1990 based on the discovery of blond synthetic fibers they claimed must have come from the woman’s wig. But the theory was shot down by Special Agent Michael P. Malone, at that time the top hair-and-fiber examiner in the FBI crime lab. In his affidavit in the MacDonald case, Mr. Malone said the fibers he examined came from dolls and couldn’t have come from a woman’s wig.

In the course of his evaluation of the fibers in the MacDonald case, Mr. Malone also examined a human hair from the crime scene that he said was "forcibly removed and appears to have a piece of skin tissue attached" to it. At the time, Mr. Malone said the hair couldn’t be microscopically identified and was too old for standard DNA testing, which was the only kind then available.

Suddenly, in 1997, the new mitochondrial DNA technique—which could be used on such a piece of evidence even if no cell nuclei were present— offered Dr. MacDonald a "last-gasp claim," says Andrew Good, one of his defense lawyers. Meanwhile, in the wake of the Justice Department’s April report on the crime lab, Mr. Malone’s credibility was now in question.

Back to Court

The Justice Department report, which criticized 13 FBI crime-lab analysts, was particularly tough on Mr. Malone for giving inaccurate testimony in an unrelated case. Meanwhile, a front-page article in The Wall Street Journal also raised questions about the credibility of Mr. Malone’s testimony in a number of cases, including Dr. MacDonald’s. The Journal article reported, among other things, that Mr. Malone’s conclusion about the origins of the blond fibers found at the MacDonald crime scene wasn’t supported by other experts whom Mr. Malone had interviewed or by textbooks available in the FBI’s own library.

Believing these revelations might influence a judicial panel, Dr. MacDonald’s lawyers again asked a federal appeals court to reopen the
case, this time seeking the right to conduct mitochondrial DNA testing on crime-scene evidence. To help with this new approach, they brought in DNA specialist Barry Scheck, best known for his role in cross-examining the government’s DNA expert in the O.J. Simpson case.

In October, the court, without comment, granted the request. It was Dr. MacDonald’s first court victory of any kind in almost two decades. "It is poetic justice that the same mitochondrial DNA testing that the FBI is using as a sledgehammer to prosecute people is the way I can now get back into court in my murder case," says Dr. MacDonald, who is serving a life sentence in Sheridan, Ore.

The fateful test in his case is expected to take place early next year.

Results are due about one month later