By A.C. Thompson

Fact checker: Geneticist-turned-attorney Bicka Barlow is pushing the SFPD's crime lab to reveal more data about its scientific methods. Photo by Lori Spears

Case in point: an ongoing evidentiary tug-of-war pitting the San Francisco Public Defender's Office against the San Francisco Police Department's crime lab and the District Attorney's Office.

The dispute involves 10 hardcore criminal cases, with charges ranging from kidnapping to sexual assault to homicide. Because DNA evidence plays a central role in all the cases – and could mean the difference between acquittals and life sentences – attorneys for the defendants are asking how the lab handles DNA samples.

Spearheading the effort is Bicka Barlow, a geneticist turned lawyer who wants to know whether police department DNA analysts are using valid scientific techniques, something that hasn't always happened in other towns, like, for example, Houston and Oklahoma City, where supposed experts have used junk science to put innocent people in prison cells.

Prosecutors are balking at Barlow's request, saying she's on a "fishing expedition" for "irrelevant" information.

But there are good reasons to be a little skeptical about the local lab. During the 1990s the lab was buffeted by a series of screwups – including a technician who falsified test results in drug cases, a scathing report by the Civil Grand Jury, and a judge who questioned the scientific soundness of its DNA readings.

Laid-back and endowed with a slight Southern twang, Barlow was a consultant on the cleanup of "Superfund" sites – areas laden with huge amounts of toxic crap – before becoming a defense lawyer. Since last August she's played a dual role at the Public Defender's Office, acting both as a trial attorney and an adviser on DNA evidence for other attorneys.

Matching two chunks of DNA isn't a simple, push-button endeavor, like throwing a couple of chicken nuggets in a microwave, she noted. "It's a very complex process," Barlow told the Bay Guardian. "There are literally hundreds of steps. And at every step of the way there's the potential for errors" – both human and machine-generated.

So she's asking the crime lab to turn over a pile of internal paperwork, including maintenance records for two key DNA-processing machines, quality-control logs for the machines, and audits of the lab conducted by outside inspectors.

Barlow wants to scour the records for any technical bugs that might be haunting the machinery. One of the devices in question, called a thermalcycler, uses heat and cold to amplify DNA, creating millions of copies of the genetic chain. Barlow says fluctuations in temperature beyond certain parameters can affect the reliability of a thermalcycler.

The other machine at issue is the ABI 310 Genetic Analyzer. In court briefs, Barlow claimed the equipment, which looks like a small refrigerator and is manufactured by Foster City firm Applied Biosystems, "has certain operational problems such as electrical spikes, camera failure and robotic failure that can impact the results."

Her concern with the ABI 310 is backed up by Dr. Simon Ford, a biochemist with Lexigen, a forensic consulting firm based in San Francisco. Ford has personally come across two crucial malfunctions, instances where the device tested the wrong sample. "What I saw happened in two separate cases, in two separate labs," he told us. "It's a very significant error."

Barlow is also requesting copies of the proficiency tests taken periodically by SFPD DNA experts, to see just how much expertise they possess. None of this sits well with the crime lab. In a sworn declaration, lab director Cydne Holt said locating and copying the "requested material will take at least 120 working hours for the analysts."

Assistant district attorney Braden Woods has been fighting Barlow since November. In addition to labeling the whole exercise a "fishing expedition," he's described her requests in court briefs as "overbroad" and "not material." According to Woods, the evidence already turned over to Barlow and company indicates the DNA equipment was working correctly when the various samples were run.

Woods also said the proficiency tests aren't pertinent. "The issue is not whether the forensic DNA analyst performed correctly two years or six months ago when performing exams. Rather, the issue is whether [s]he performed correctly in this case," the prosecutor argued in court papers.

Debbie Mesloh, a spokesperson for the D.A.'s Office, said, "Our biggest concern is that we don't want cases delayed. We felt the request went above and beyond what the lab has the resources to provide."

For an outside opinion, we contacted Dean Wideman, a forensic expert in San Antonio, Texas, who's hunted for genetic clues in thousands of cases. In Wideman's view, Barlow's efforts aren't out of the ordinary. "Those are the typical things to request so a defense expert can make sure everything is on the up-and-up," he said. "That's not atypical."

Though Wideman doubts Barlow will uncover any serious snafus, he's quick to note that DNA technology, viewed by the public as some kind of crime-solving magic bullet thanks to some high-profile cases and TV shows like CSI and Court TV's Forensic Files, is far from infallible. Wideman was called in on one case after lab analysts "contaminated a sample with their own DNA and failed to report it," tainting the whole process.

On March 14, Superior Court Judge Mary Morgan ordered the lab to open its doors to Barlow to allow her to photocopy much of the information she requested; more than two weeks later she and Woods are still at loggerheads about exactly what she's entitled to, and Barlow figures an appeal is imminent.

"My sense is that the people in forensics don't understand what my job is," she told us. "They think what I'm doing is harassment. They don't understand I have an obligation to question everything they do. It's not personal."

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