DNA Witness Concedes a Lack of Expertise


The expert brought in by lawyers for O.J. Simpson to debunk a host of scientific test results in the murder case acknowledged Thursday that he has no special expertise in collecting or analyzing crime scene evidence but said one form of DNA testing used by prosecutors in the case is unreliable.

But John Gerdes, a microbiologist from Denver, cited his extensive experience running a medical laboratory and told jurors they should not trust at least some of the prosecution’s DNA test results, most notably a set taken from the interior of Simpson’s Ford Bronco.

Because the car was broken into while it was in police custody, “you can no longer have any scientific confidence” in the samples taken from inside the Bronco, Gerdes testified just before concluding his testimony for the defense.

Gerdes’ testimony, guided by Simpson attorney Barry Scheck, represented some of the most important evidence that the jury has heard on behalf of Simpson, who has pleaded not guilty to the murders of Ronald Lyle Goldman and Nicole Brown Simpson.


The prosecution has built much of its case around scores of DNA tests that show blood resembling O.J. Simpson’s at the scene of the crimes, and drops with genetic markers identical to those of the victims in his car, on a glove found outside his home and on a sock discovered at the foot of his bed.

Gerdes has helped the defense raise questions about a number of those tests by testifying that the Los Angeles Police Department laboratory was riddled with chronic, serious contamination. But on Thursday, Deputy Dist. Atty. George (Woody) Clarke put the scientist through a gentle, persistent--if sometimes highly technical--cross-examination, attempting to undermine Gerdes’ credentials and to suggest that his conclusions about possible contamination of samples in the Simpson case should not be trusted.

“You have never taken a class in forensic science?” Clarke asked near the beginning of his cross-examination.

“Correct,” Gerdes responded, his buoyancy of a day earlier giving way to a more reticent, defensive demeanor.

“You have never taught a class in forensic science?” Clarke continued.

“Correct,” Gerdes said again.

“You have no training whatsoever in police evidence-gathering techniques, correct?” Clarke then asked.

“No formal training,” Gerdes acknowledged.


Continuing his cross-examination, the prosecutor attempted to portray Gerdes as a hired gun whose lab collects $100 an hour--and expects to be paid at least $30,000 for its work in the Simpson case--for fighting against the use of a form of DNA testing known as PCR analysis in criminal cases. Clarke noted that in 23 cases in which he has testified, Gerdes always has opposed the forensic use of PCR analysis; the prosecutor also drew upon a variety of sources to suggest that Gerdes’ opposition to the technology is ill-founded.

After Gerdes warned of the perils of sample degradation, for instance, Clarke pointed out that PCR was used to identify the remains of American war dead during the Persian Gulf War and has even been employed to analyze the remains of mummies.

“Would you consider that a degraded sample?” Clarke asked about material taken from mummies.

“I’m sure it is,” Gerdes responded with a smile.


Although that exchange drew smiles from some jurors and from Superior Court Judge Lance A. Ito, much of the cross-examination was highly technical, and some panelists seemed to lose interest. One juror spent part of the morning leafing through old notes while a black man who sits in the front row--the same juror whose illness last week forced a recess in the proceedings--appeared lost in thought, staring into the distance and not taking notes at all.

During the afternoon session, two jurors fought to keep from nodding off, although near the end of the day, when testimony turned back to the question of contamination at the LAPD lab, they snapped back awake and more jurors began taking more notes.

The 14 remaining members of the Simpson panel--a group that started at 24 but dwindled to its current size after a series of juror investigations--has been cut off from the outside world since January. Their access to friends and news is strictly monitored, with all references to the Simpson case cut out of the newspapers they receive.

But Jerrianne Hayslett, Superior Court spokeswoman, said Thursday that she had been informed by the Sheriff’s Department that no other articles are being clipped from the jurors’ papers. As a result, jurors who are hearing testimony about the problems with the LAPD lab also are being allowed to read news reports about other LAPD-related controversies such as the recent shooting of a teen-ager in Lincoln Heights.


“That stretch,” said Hayslett, “is not being made.”

The extensive questioning by Clarke postponed for at least a day the eagerly anticipated faceoff between Deputy Dist. Atty. Rockne Harmon and a defense expert, Kary Mullis, a Nobel Prize-winning scientist who invented the PCR technology that Gerdes spent much of the day analyzing while Mullis sat a few feet away, listening closely.

At one point Thursday, Mullis’ name surfaced in passing. When it did, Clarke pointed him out and asked Gerdes whether he recognized him.

Gerdes said he did, and Mullis sat up straight, smiling impishly, raising his eyebrows and waving at the jury. A few jurors smiled back.


As the day continued, Mullis followed the back-and-forth between the prosecutor and scientist closely. For much of the session, he gently cradled his face in his left hand and stared at the participants, his eyes darting back and forth between them. Occasionally, he smiled and nodded approvingly at Gerdes’ answers.

Mullis is a controversial figure in a case filled with controversies. His scientific work with DNA technology laid the foundation for many of the tests that the prosecution has used to implicate Simpson in the crimes. But Mullis has expressed grave reservations about the use of his work in the criminal justice context, and he is expected to testify about those reservations in the coming days.

Mullis’ Nobel Prize and other scientific credentials make him an appealing witness, but his unorthodox views--he disputes the commonly held wisdom that HIV causes AIDS, for instance--along with his fondness for illegal drugs make him a prime target for cross-examination. Harmon has vowed to put Mullis through his paces, a process that could begin today or next week if the defense sticks by its determination to put the scientist on the stand.

As he left the courthouse Thursday, however, Simpson attorney Johnnie L. Cochran Jr. hedged on the defense’s previous commitment to calling Mullis as a witness. Instead, Cochran said the defense lawyers would meet today to discuss whether they needed Mullis’ testimony.


In some respects, Gerdes has laid the foundation for Mullis’ testimony, establishing the defense contention that jurors should be skeptical of any work performed by the LAPD lab--to be followed up by an acclaimed scientist intended to convince them to doubt the underlying science as well.

Gerdes made that point, suggesting that PCR technology, although widely used in medical applications by his lab and others, was not appropriate for use in criminal cases.

Although describing PCR as a “sound scientific principle,” Gerdes said, “basically my opinion is it is inadequately controlled in forensic testing at the moment, and it hasn’t been adequately validated.”

The technology, he added, “has some risks with it, and I think it’s important for the jury to know about those so that they can make a reasonable decision as to how much weight to put on this kind of evidence.”


Scheck completed his examination of Gerdes on Thursday morning, and drew a rare compliment from Ito. Speaking outside the jury’s presence, Ito credited Scheck with making important points during his questioning.

Ito, in denying Scheck’s request to limit the cross-examination of the scientist, commented: “I think you’ve downplayed the breadth and scope and effectiveness of your own presentation [Wednesday]. I think you’ve opened a whole line of questioning regarding the entire evidence collection process, how it was processed at the LAPD lab, and calling into question all of the subsequent results.”

Legal analysts agreed.

“Gerdes’ testimony Wednesday was the most powerful the defense has presented so far,” said Peter Keane, San Francisco’s chief deputy public defender, who was in court Wednesday and who watched the testimony Thursday as well. “Gerdes’ testimony essentially casts into question all the prosecution’s DNA findings. Since the heart of the prosecution case is DNA, if their findings remain in doubt then there’s a good likelihood of an acquittal for Simpson.”


But experts also gave Clarke credit for helping to mute the impact of Gerdes’ testimony.

In his characteristically low-key way, Clarke combined his points about Gerdes’ lack of specific training in the area of forensic applications of DNA technology with gentle derision of his professional credentials. Gerdes testified, for instance, that before going to Immunological Associates of Denver, where he is now the clinical director, he worked for a community college and pineapple company in Hawaii and then the Veterans’ Administration in Denver--positions that Clarke suggested were not typical for an eminent scientist.

Those questions and others challenging Gerdes’ analysis of work by the LAPD often contained a hint of contempt, but rarely did tempers rise. When Clarke suggested that Gerdes was treating a possible mistake of his own lightly, the scientist seemed to grow agitated: “You’re confusing it,” he snapped. But that flare-up passed quickly, and neither man raised his voice then or later. Keane and said the prosecutor’s cross-examination yielded mixed results.

“Clarke has attempted to demonstrate that Gerdes does not have sterling credentials and background and has succeeded to some extent in showing that Gerdes is not a highly credentialed scientist,” the public defender said. “But he hasn’t destroyed his credentials; Gerdes remains a Ph.D. in microbiology and he runs a DNA lab.”


Other analysts rated Clarke’s cross-examination more highly, crediting him with raising significant questions about the scientist’s credentials and with suggesting that Gerdes was not reliable enough to undermine the prosecution’s DNA test results.

“I think that Woody Clarke has done an excellent job,” said Paul Mones, a Santa Monica defense lawyer and DNA specialist. “While Barry Scheck pointed out some of the possibilities that might lead one to believe there was a ‘cesspool of contamination’ at the LAPD lab and seemingly undercut the prosecution’s use of DNA, I think Woody Clarke has matched him point for point in showing the vulnerabilities of this witness.”

Times legal affairs writer Henry Weinstein contributed to this story.