Case Not Closed
Imagine, for a moment, that you are impaneled on a jury, listening to detailed, complicated DNA evidence implicating the defendant in a rape--or a murder. Blown-up charts and graphs rest on easels in front of you. A scientist is pointing at different areas on the placards. The expert is telling you that these little blips and squiggles show a likely match between the defendant's DNA and that found in samples at the crime scene, or on the murder weapon. What do you make of the explanations? What these blips and squiggles mean, you are told, is that there is only the slimmest chance that another person, randomly selected, would also have DNA that matched.
If you're like many jurors, you might be convinced of the defendant's guilt. Faced with the evidence--dense, difficult to understand, specific, and scientific--jurors are often immediately persuaded by DNA tests.
"Jurors attach a great deal of significance to this evidence. That's one of the reasons we have to be so careful about it," explains attorney Joe Margulies. "Jurors hear 'DNA' and think, 'That's it. He's guilty.'"
For those of us who are not scientists, we hear about DNA evidence and we assume it's rock solid. We've heard the stories of death-row inmates who were cleared at the 11th hour, thanks to new DNA evidence. We've heard the stories of old, unsolved cases where the culprits were finally discovered and convicted, thanks to new DNA evidence. We take for granted its veracity. If a scientist tells us the DNA matches, who are we to argue?
For precisely those reasons, Margulies contends, DNA evidence must be tested, retested, and independently proved reliable. That contention is at the heart of two appeals currently being considered by the Minnesota Supreme Court. Until then, the state's forensic experts at the Bureau of Criminal Apprehension are using a DNA test that in the end might or might not constitute adequate evidence to convict someone in a Minnesota court.
The most dramatic potential outcome is that the test would be found inadequate--and as a result, suspects can't be convicted and criminals already imprisoned must be retried. But even if the tempest ends up being a legal technicality (a far more likely scenario), it means a growing backlog of trials as prosecutors wait to proceed until they know whether DNA evidence can be introduced. Just last month in Hennepin County, for example, a judge ruled, reluctantly, that the DNA test used by state forensic scientists would not be admitted into evidence in eight pending trials.
The bottom line? Until the justices decide whether they agree with the arguments of Margulies and the other attorneys involved in the appeals, any criminal case that relies on DNA evidence, anywhere in the state, could be delayed.
To Minnesota's Bureau of Criminal Apprehension (BCA), the "polymerase chain reaction-short tandem repeat" (PCR-STR) test looked like a significant advance in methods for processing DNA when it arrived on the scene in the late 1990s. The BCA had been using DNA tests to gather evidence since 1991, but this new test promised to be both more informative and more efficient.
Using a new technology, the test required only a tiny amount of evidence, replicating a billion copies of the genes in question so that investigators could more easily create a profile of the underlying DNA. With a sample (a bloodstain, saliva from a cigarette butt, a single hair) just one-twentieth the size of that needed for previous tests, the PCR-STR test could offer proof that astoundingly few randomly selected people would likely have DNA matching any given sample. Just one in a quadrillion, in fact. While that doesn't necessarily implicate a particular suspect, it does serve to narrow the field of possibilities. "We get so much information out of a very, very small sample," explains James Iverson, the BCA's forensic science supervisor.
The prospect was exciting, for the BCA investigators and for prosecutors. Every scientific advance potentially increases the amount of information that can be determined from crime-scene evidence. More detailed scientific data could only bolster investigations and get closer to the truth about what transpired. Even long-dormant "cold cases" might finally be laid to rest, aided by new evidence made available by the test.
As the BCA set out to implement the new DNA test, Iverson says, it looked at two companies that provided kits to do the testing, Applied Biosystems (also known as PerkinElmer) and Promega. The BCA selected Applied Biosystems. "At the time, Applied Biosystems was farther along with the setup and instruments," Iverson explains. The BCA, he continues, did at least a year's worth of testing in order to prove that the kits worked and gave consistent results, and in 1999 the agency launched the new method of gathering DNA evidence. "Once you start going down one road," Iverson adds, "it's hard to go backwards."
Today, Iverson says, some 200 labs across the nation use PCR-STR testing, and 85 percent of them use the Applied Biosystems kits. According to Hennepin County prosecutors, the test has been challenged in courts nationwide, with appellate courts in 26 states deciding to admit the evidence. To the BCA and prosecutors, the test's reliability is a foregone conclusion. "I have zero concern," says Senior Assistant Hennepin County Attorney Steve Redding, a prosecutor who has used evidence from the new procedure in criminal trials.
But today, it's exactly that system that has been called into question in Minnesota. At issue is the test's underlying chemistry. Arguing that this information is proprietary, Applied Biosystems has never publicly disclosed the compounds, called primer sequences, that make the DNA test work. (Its competitor, Promega, made its compounds public, Redding points out, only after a court challenge in 2000.) The BCA and prosecutors argue that the sequences don't matter as long as the test results are accurate.
Redding offers an analogy: "Do you need to know the chemical compound of the toner in the fax machine to know that the fax machine accurately and reliably does what it's supposed to do? I don't think you do."
Margulies and other defense attorneys contend that you do need those formulas in order to independently validate the test. In fact, they argue, certain accepted scientific guidelines demand it. Without impartial proof that the test works, everyone in the system is simply expected to take the company's word for it. "Why go with a company that refuses to disclose its underlying methodology?" Margulies asks. "A company that has a financial stake in the outcome?"
Margulies appealed the issue of the DNA test on behalf of Raymond Traylor, who in October 2000 was convicted of second-degree assault and possession of crack cocaine after the state was allowed to introduce DNA evidence from the PCR-STR test at trial. On November 13, 1999, a woman named Debra Clemons called Minneapolis police and reported that Traylor had stabbed her and was sleeping in her home. When police arrived they found a bloody knife and a small amount of cocaine in Traylor's pocket. He was charged with second-degree attempted murder, second-degree assault, and a fifth-degree controlled-substance offense.
At trial Traylor denied that he had stabbed Clemons and, in fact, that he had ever possessed the knife. The state introduced DNA evidence it said established that the blood on the knife and on Traylor's pants contained the same DNA as Clemons's blood. The jury convicted Traylor of the assault and drug charges, and he was sentenced to more than eight years in prison.
In March the Minnesota Court of Appeals agreed that the trial court made a mistake when it allowed the test results to be used as evidence. Specifically, the justices held that the trial court should not have admitted the evidence because the state had not proven that the PCR-STR test procedures complied with accepted standards. The court of appeals also ruled that error in Traylor's case was harmless; in essence, that he would have been convicted even without the DNA evidence.
Margulies disputes this. "It was the most important evidence in the case," he argues. "Until it's freely and openly tested, it's not admissible. Unless you have independent validation, you don't use it to deprive people of their liberty."
The Minnesota Supreme Court has agreed to review the Traylor case, and, as Margulies requested, it will also examine whether admitting the DNA evidence was indeed irrelevant to the jury's verdict. In addition, the supreme court is also currently reviewing the June 2001 first-degree murder conviction of Tony Allen Roman Nose, in which issues with the same DNA test were also raised.
The uncertainty last month led Hennepin County District Court Judge Thor Anderson to deny admission of the DNA test in eight pending cases (a decision the state has appealed). Though Anderson barred the DNA evidence in those cases, he did so bitterly: "The necessity of deciding the case in this way is an unmitigated tragedy. It certainly is not justice," he wrote in his June 19 decision. "The overwhelming weight of the evidence is that the system used by the Minnesota BCA to match DNA samples in these cases is astoundingly accurate. Subject to rare human error that creeps into any endeavor the system is virtually foolproof. It is used by reputable forensic and other labs the world over. Its most vociferous critics insist on its use when it serves their purpose."
But despite the controversy--and the complaints of defense attorneys, who say the problem could be solved if the BCA would just switch to a test that can be validated--the state lab plans to continue using the current test until a supreme court decision forces a change. A decision is expected by the end of the year.
Iverson says the decision to continue using the current test was made partly because it would cost too much money and take too much time to switch to Promega's kits. And the lab can't go back to using the older DNA tests that preceded the PCR-STR test, because it got rid of the necessary equipment years ago. "We're not going to do a knee-jerk here," Iverson says. "As of now we're performing the testing and giving the results. Whether they're available to use in court or not will be up to that individual judge at the time."
That move could cause a bottleneck in trials, as prosecutors wait to see if they'll be able to introduce DNA evidence. The Hennepin County Attorney's Office has 23 cases on hold at the moment; it's unclear exactly how many cases across the state may hinge on DNA evidence, or how many trials may have to wait until the supreme court rules.
It's also unclear how many convictions statewide were obtained using the questionable test. Since 1999, Iverson says, the test has been used to gather evidence in some 1,500 cases.
But defense attorneys say that the prosecutors' gloomy picture and the BCA's claim that it would be too difficult to switch to a different system of testing are simply a way to prejudice the public and, possibly, the supreme court. "This is a not-so-subtle attempt to influence the supreme court's decision on this," opines Assistant State Public Defender Steve Russett, the attorney handling the Roman Nose appeal. "The state's in a jam. The BCA chose to get rid of its old equipment. They should not have put themselves in a position where they couldn't go back to the previous test before the supreme court ruled on this new test. They made their own mess."
Besides, one might argue, justice should not be a matter of convenience. If the supreme court does rule that the new test is inadmissible, some of the convictions that came after the evidence was introduced might be overturned, and those defendants would receive new trials. That would be done only on a case-by-case basis, depending upon the significance the DNA evidence played in reaching a verdict. "That may be burdensome on the system," Russett says. "But that's what our system is supposed to be about."
And even though that would mean that the rules in Minnesota are stricter than in other states, Russett says that's not a bad thing. "Minnesota has been a leader on this issue in the past," he says. "I don't think it should become a follower at this point."
For his part, Margulies says he's prepared to abide by the court's decision. "If it's independently validated, believe me, I'll be on the street corner saying let's use it to convict the guilty and free the innocent," he says. "But until then, we just don't know."
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