Lab Director Continues Primer on DNA Tests

Stopping just short of introducing DNA test results in the murder trial of O.J. Simpson, a key prosecution witness continued her meticulous science lecture Tuesday, telling jurors how the tests are performed and explaining why contamination would not cause DNA to change and falsely implicate a suspect.

That testimony, from scientist and prosecution expert Robin Cotton, was important to the government’s case and laid the groundwork for its most important evidence--the test results that authorities say will link Simpson to the June 12 murders of Nicole Brown Simpson and Ronald Lyle Goldman.

Among those results are stains from the scene of the crimes, the inside of Simpson’s car and his Brentwood estate. Outside the jury’s presence Tuesday, the lawyers discussed some of those results, including several blood mixtures that prosecutors say suggest stains with blood from both victims and Simpson himself.

But the day ended Tuesday without Cotton, director of Cellmark Diagnostics in Germantown, Md., presenting the results of any tests performed on samples from the scene of the crimes or from Simpson’s car or estate. As the day concluded, jurors were shown copies of X-rays that portrayed results of genetic tests performed on the blood samples taken from Simpson and the two victims.

What panelists did not see were the evidence samples that were compared to the blood from the defendant and victims using various forms of DNA testing. That evidence is expected to be introduced today, and it will mark the first time that jurors have seen for themselves the much-discussed DNA evidence in the case.

Authorities have long said that DNA tests of blood drops from the scene contained genetic markers suggesting that Simpson was the source, and they say that blood from Simpson’s car and estate resembles that of both victims.

Simpson has pleaded not guilty to charges that he murdered his ex-wife and her friend, and his attorneys have aggressively challenged the credibility of the physical evidence amassed against their client. Among other things, the Simpson team has suggested that evidence was gathered so sloppily that test results cannot be trusted, and it has accused police of tainting some evidence to frame the former football star with the murders.

Although the jury did not hear about DNA test results Tuesday, outside the panel’s presence prosecutors previewed some of the results that they hope to introduce this week

According to Deputy Dist. Atty. Rockne Harmon, one of the prosecution’s DNA legal experts, a stain found on the bottom of Goldman’s shoe suggests a mixture of his blood and that of O.J. Simpson. Harmon added that a glove found outside Simpson’s estate contains blood consistent with that of both victims and the defendant, and that the center console of Simpson’s car contained a mixture of blood consistent with that of all three people.

“There’s only one defendant at the end of the table, and his type is consistent with the mixture that was obtained there,” Harmon said of one bloodstain. Simpson glared back at the prosecutor as he leveled that accusation.

The statistical significance of those discoveries is hotly disputed, however. According to the defense, one bloody mixture found on the steering wheel of Simpson’s car could have come from millions of people and thus may shed little light on the actual source. Prosecutors said, in fact, that blood on the steering wheel may even include genetic material from someone unconnected to the case.

The samples discussed out of earshot of the jury represent the only instances in which prosecution tests have suggested a mixture of the blood of the suspect and the victims, and defense attorneys have mounted an objection to the way prosecutors want to introduce the results. Superior Court Judge Lance A. Ito said he would consider the objection overnight and indicated that he would probably rule this morning.

Suspense Builds

Although the results of those DNA tests have been eagerly anticipated since opening statements in the trial, Deputy Dist. Atty. George Clarke kept up the suspense all day Tuesday. He instead posed questions intended to make the results more comprehensible and to head off expected defense challenges.

Clarke had hoped to begin discussing results just before the end of the day, but frequent objections from Peter Neufeld, one of Simpson’s DNA lawyers, forced the prosecutor to backtrack and spend more time eliciting basic testimony about how certain statistical calculations are made. Because of that, the introduction of results was pushed back.

As the day neared its conclusion, Simpson and his attorneys huddled at the defense table, passing around X-ray film that prosecutors gave the jury to inspect. At one point, Simpson burst into laughter, then quickly covered his mouth and strained to keep a straight face.

The postponement meant that jurors spent two full days hearing testimony with only passing references to the Simpson case. And although analysts have widely praised Cotton and Clarke for their skillful coordination and smooth presentation, some also warned that the jurors may grow impatient--especially as Cotton’s testimony has ventured from the relatively straightforward issue of genetics to more arcane, statistical topics.

“Robin Cotton is a very good witness,” said Myrna Raeder, a Southwestern University law professor who has researched DNA litigation. “She’s everyone favorite 10th-grade biology teacher. But Tuesday we went from molecular biology to population genetics. It’s probably overload for most of the jurors.”

Ending the day without reaching results, Raeder added, meant that the session concluded “with a whimper, not with a bang.”

At a news conference Tuesday afternoon, Los Angeles County Dist. Atty. Gil Garcetti said he was pleased by reports of the jury’s receptiveness to the initial day of DNA testimony and added that he hoped the attorneys would hold that attention despite the sometimes technical nature of the subject. In court, most of the jurors appeared to be paying close attention; many took notes and some copied whole prosecution charts onto their pads.

“Yesterday we had jurors paying very good attention,” Garcetti said. “They looked real interested. Hopefully, we have them today.”

‘It Doesn’t Happen’

Although the testimony did not get as far as Clarke had hoped, Cotton spent the day on the stand defending her lab’s proficiency record and explaining for the jury why improper collection techniques or contamination of blood samples would not cause them to point to someone other than the true source.

Both of those points are important underpinnings of the prosecution’s case, and Cotton explained them clearly and crisply, speaking directly to the jurors and illustrating complicated points with simple, carefully drawn diagrams.

Clarke had asked the scientist to explain the effects of degradation on DNA samples Monday, and he returned to the topic Tuesday, asking her why leaving blood outside or exposing it to the elements would not cause it to falsely implicate an innocent person.

“There is no environmental effect that can work to simply change one type and make it become another,” Cotton testified. “You may lose the type altogether. You may degrade the DNA so much that you can’t type it, but you won’t just change types from one to another. It doesn’t happen.”

Bracing for one possible defense attack, a challenge to the reliability of Cellmark’s analysts and procedures, Clarke posed a series of questions about how the lab had fared historically in proficiency tests.

Neufeld and his longtime legal partner, defense lawyer Barry Scheck, previously have challenged Cellmark’s reliability, and Clarke’s questioning was intended to preempt the defense from raising the topic first.

Cotton admitted that the lab’s record was not perfect: In 1988 and 1989, Cellmark incorrectly identified one blood sample in each of the annual tests. Cotton acknowledged those mistakes and said intense efforts were made within the laboratory to determine what went wrong.

A number of changes to the procedure were made after those two failures, she said, including a requirement that analysts not work on evidence samples at the same time that they work on blood samples submitted by suspects or victims. Since those changes went into effect, Cotton testified, there have been no more failures during the semiannual proficiency tests administered to each of the lab’s analysts.

Ito Angry

Cotton’s testimony has proceeded smoothly for the prosecution as it attempts to lay the foundation for the all-important test results, but one technical glitch in Tuesday’s proceedings caused Ito to display testiness in front of the jury.

When a wireless microphone worn by Cotton caused static through the courtroom, Ito asked for the device. Then, when he realized that Cotton no longer had a microphone at all, Ito angrily threw the wireless microphone on the floor beneath his bench before storming out of the room, muttering, “Fix it.”

Court resumed a few minutes later, and Ito apologized to the jury for the delay, although he did not explain his flash of anger.

“Ladies and gentlemen, my apologies to you for our short delay, but you need to hear what’s going on,” Ito said. “Let’s proceed.”

Ito’s impatience with the long foundational questioning flared later in the afternoon as well. Clarke occasionally repeated questions as he launched new areas of questioning, and Ito fidgeted noticeably.

“Let’s move it along,” he admonished Clarke at one point. Cotton flinched slightly at the judge’s angry tone, but the lawyer merely nodded slightly and pressed forward with his questioning.

Later, when Neufeld tried to object to one line of prosecution questioning, saying it was hard to follow, Ito shrugged off that complaint.

“There’s nothing confusing about this,” Ito said.

Jurors Under Scrutiny

At the end of Tuesday’s session, the attorneys and Ito retreated into the judge’s chambers, where they were joined by Los Angeles County Sheriff’s Department deputies who oversee investigations into jurors.

Although those sessions are held in private, a source familiar with the case said that at least two more jurors remain the focus of allegations. One, the 38-year-old woman said to have been a leader of the jury strike, was accused of discussing her opinions about Simpson, a claim that is under investigation but has not been substantiated, the source said.

That same juror previously has expressed concern about her ailing husband, but it has been more than a week since that issue was raised and she has remained on the panel.

The source added that another juror, the recently promoted alternate who took the place of the last excused panelist, has been accused of expressing opinions about the case. Those allegations, the source said, come from at least one colleague who works with the juror in the Los Angeles County assessor’s office.

So far, six of the panel’s original 24 members have been excused for various reasons. Some commentators have expressed concern that there may not be enough jurors to complete the trial, which is expected to last through the summer. Tuesday, Garcetti said he hopes that the prosecution will complete its case by the end of next month.

Originally, Garcetti and his office had hoped to wrap up their case by the end of April, an estimate that has given way to prolonged questioning of witnesses. Even the latest guess, Garcetti conceded, may prove to be optimistic.

Times legal affairs writer Henry Weinstein contributed to this story.