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Gabriel, who earlier this year departed the lab for a position at Applied Biosystems, a genetic-testing products firm in Foster City, first learned of the ASCLD report from SF Weekly and initially said he might be willing to discuss it. After receiving the report from a reporter, he did not respond to further requests for comment.
Marc Taylor, president of Technical Associates, Inc., a private crime lab in Ventura, says DNA sample mixups aren't unheard of in the forensics business. What makes the chain of events in San Francisco so disturbing, he says, are the steps that were taken to conceal it — first the relabeling of test tubes and destruction of lab records, then Mudge's letter flatly denying any knowledge of the incident. These, more than the switch itself, are symptomatic of a lab that has no place handling evidence in criminal cases, Taylor says.
"For every one of those things that are discovered, there are dozens or hundreds that could have happened. That could result in a false conviction of somebody," he says. "If you're going to be switching things, if you're going to be hiding things, if you're going to be saying things didn't happen, you've lost your credibility. That laboratory should be shut down."
While the idea of a switched DNA sample in a homicide case is titillating stuff, it wasn't the first time the lab's workers had faced accusations of unethical conduct. In fact, at the beginning of 2008, another DNA analyst would make statements under oath before a grand jury that would later give rise to a complaint to Gascón — and yet another internal-affairs investigation.
In that case, criminalist Cherisse Boland gave testimony implicating two young men in a vicious murder. Yet they would later be acquitted, and troubling indications would surface that both Boland and the SFPD had ignored evidence that could lead to the real killer.
On the morning of Sept. 2, 2007, Byron Smith was gunned down in a stranger's garage on Velasco Avenue after fleeing from two men on bicycles. In the aftermath of the murder, police inspectors arrested Emon Brown and Joc Wilson, who they believed had executed Smith as part of a turf war between rival gangs in the Sunnydale Projects.
While investigators located an eyewitness who was willing to testify, her usefulness was questionable. For one thing, she said Wilson wasn't one of the shooters. To help make their case, the cops turned to physical evidence, in the form of DNA swabs gathered from the handle-grips of the bicycles supposedly used by Smith's killers, which were found at the crime scene.
On Dec. 14, 2007, Boland reported that she had a match. Two of them, in fact: In a write-up of her lab examination, she declared that both Wilson's and Brown's DNA had been found on the bikes' grips, along with the DNA of an unidentified third man.
On Jan. 31, 2008, she appeared before a grand jury, and under questioning from Assistant District Attorney Diana Garcia, offered sworn testimony echoing the findings of her report. The grand jury went on to deliver indictments of Wilson and Brown.
But there was a weakness in Boland's report and testimony, and it was one that would not be obvious to any but the expert eye. Everything she said was technically true — both Brown and Wilson matched with small traces of DNA on the grips. But a significant result of the analysis was not made clear: The third, unknown person had left much more of his DNA on the bikes, making him what forensic scientists call the "major contributor" of DNA on the crime scene evidence.
The expert eye that caught this oversight belongs to Edward Blake of the Forensic Science Associates lab in Richmond. In a report prepared for Tamburello, Brown's lawyer, Blake pointed out that "In her SFPD laboratory report ... Cherisse Boland failed to disclose the presence of a major DNA source. ... Apparently, Cherisse Boland also failed to inform the Grand Jury that indicted [Joc] Wilson and Emon Brown of this fact in her testimony on January 31, 2008."
Blake went on to note that the most prominent DNA profile "has not only not been explicitly disclosed, it has not been searched in national or local DNA violent offender libraries or in the DNA libraries of SFPD personnel who handle, collect, and process physical evidence."
To Blake, a highly regarded scientist who has done extensive genetic research for the Innocence Project, a national legal organization dedicated to exonerating the wrongfully convicted through DNA evidence, this didn't make sense. Didn't the SFPD want to chase down every lead? What if a search of the FBI's criminal database turned up a hit on the unknown genetic profile for a violent felon who lived in Smith's neighborhood?
"I'm going through this data and looking at this report, and I'm saying, 'What the hell is going on here?'" Blake recalls. Armed with his dissection of Boland's methods, Tamburello and Deputy Public Defender Steve Olmo, who represented Wilson, were able to get their clients acquitted of all charges in a jury trial that ended in February of this year.
Following the trial, Tamburello wrote a letter to Chief Gascón describing his concern that Boland had misrepresented evidence in her report and before the grand jury. "When a supposedly trained criminalist fails to provide a truthful scientific report about her DNA analysis of evidence, and compounds that error by giving misleading testimony before the Grand Jury, we must all question the credibility of the laboratory and supervisors responsible for implementing and overseeing the procedures designed to ensure accuracy and the reliability of DNA testing," he wrote.
"I still get upset about it," Tamburello says today. The grand jurors, he says, "were given information that was false — technically not false, but not accurate or correct. That was, in my mind, criminal."
Tamburello wasn't the only person who had qualms about the legal implications of Boland's conduct in the Brown/Wilson case. In fact, the issues he and Blake raised got the attention of Harmon, who was working as a consultant at the DA's office, where he was guiding the prosecution of cold-hit cases and training young lawyers in the presentation of genetic evidence.