DNA at Scene Matches Simpson’s, Jury Told : Trial: Results of genetic blood tests are presented for first time. Spot on his sock matches ex-wife’s, witness testifies.

Blood found near the bodies of Nicole Brown Simpson and Ronald Lyle Goldman matches that of O.J. Simpson, while stains from one of his socks match the blood of his murdered ex-wife, a biochemist testified Wednesday, giving jurors a dramatic first glimpse of the DNA evidence that prosecutors say links Simpson to the two murders.

Reviewing one of the blood drops found at the scene of the crime, Robin Cotton said the results of DNA testing point to Simpson: “When you review the DNA bands that are visible,” she said, “in each case they are consistent with the pattern that is visible in Mr. Simpson’s bands.”

Moments later, Cotton said a second drop, one from the foyer of Simpson’s home, contains the same genetic pattern--a series of visually arresting black slashes that were captured on X-rays and displayed for the judge, jury and audience Wednesday.

And at day’s end, Cotton described the genetic testing on a sock discovered in his bedroom. Neither Simpson nor Goldman could have been the source of that blood, Cotton said, but Nicole Simpson could be.

“Does Nicole Brown match the DNA found in the sock?” Deputy Dist. Atty. George Clarke asked just as the day came to a close.

“Yes,” responded Cotton, who is director of Cellmark Diagnostics in Germantown, Md.

Her conclusions Wednesday supported the prosecution’s so-called “trail of blood,” a collection of bloody stains that authorities say leads from the scene of the murders back to Simpson’s Brentwood estate and directly into his bedroom.

Missing from the trail described Wednesday were the stains taken from Simpson’s Ford Bronco. Those results are expected in coming days; prosecutors say blood with the genetic characteristics of both victims and Simpson was found in the car.

The trail of blood was the highlight of Deputy Dist. Atty. Marcia Clark’s opening statement, and it forms the centerpiece of the prosecution’s case against Simpson, who has pleaded not guilty to the June 12 murders of his ex-wife and her friend. Faced with the DNA tests, his lawyers contend that faulty collection and handling of the bloodstains--or even deliberate evidence-tampering by police--rendered the results of the tests unreliable.

The defense initially objected to prosecution witnesses describing DNA tests as having produced “matches,” given that the tests only can conclude that the number of people who could have left a stain is very small, and cannot definitively fingerprint a suspect. Superior Court Judge Lance A. Ito overruled that objection, allowing experts to testify that genetic markers “match” without saying that the samples therefore must have come from the same person.

Any testimony about allegedly matched samples must be backed up with evidence about the statistical significance of that match, Ito has said. Although Cotton has not offered that testimony yet, she is expected to do so, perhaps today.

Jurors, attentive as ever, took notes and carefully scrutinized the grainy, black-and-white X-rays as they were displayed on a large overhead screen. Some of the slashes that point to the location of genetic markers were easily visible, while others were very faint.

In contrast to the jury’s close interest, Simpson barely seemed to pay attention. Instead, he spent much of the day whispering to his lawyers and yawning as the afternoon testimony wore on.

A few feet away, Goldman’s sister and stepmother sat in the front row, looking frequently at the man accused of killing their relative. Simpson, whose mother also was in the courtroom Wednesday, did not appear to notice the Goldmans’ stares.

Anticipating a challenge to the DNA test results, Cotton meticulously has described her lab’s testing procedures and has repeated several times in recent days that even if evidence were badly handled, it would not cause a DNA test to identify the wrong suspect. Such a problem, she has testified, might result in the failure to get a discernible result from a DNA test, but it would not change the DNA or cause a person to be incorrectly labeled as the source of the sample.

Cotton also has made clear, however, that her assurances only apply to the handling of evidence by her laboratory. She cannot account for the evidence during the time it was being collected and preserved by the Los Angeles Police Department. Previous prosecution witnesses have testified that there was no evidence of tampering with any samples while they were in the possession of the Police Department.

Blood Mixtures

Finally ending suspense that has built since early this week, Cotton first disclosed the DNA test results just before the lunch break, capping a morning session that had been delayed by an hourlong argument over how prosecutors could introduce results of tests suggesting that certain drops of blood were mixtures.

During that argument, defense attorneys objected to the prosecution’s proposed approach for dealing with those samples. Immediately at issue were two blood drops, one from Goldman’s shoe and another from the steering wheel of Simpson’s car.

Prosecutors say the drop on Goldman’s shoe includes genetic markers consistent with a mixture of his blood and that of Nicole Simpson. Although prosecutors did not say that that drop contains genetic markers suggesting the presence of Simpson’s blood, a single drop with a mixture of the blood of the two victims could bolster the government’s theory that a single knife was used to kill both.

The drop on Goldman’s shoe, Detective Tom Lange said during his testimony, seemed to be a so-called “castoff,” or a drop that fell from the murder weapon. If the evidence suggests that that blood from both victims was in that drop, it could help convince jurors that only one weapon was employed--helping to debunk defense suggestions that the murders were committed by more than one assailant.

Cotton testified about that drop Wednesday afternoon, explaining why she believes the blood from Goldman’s shoe could have come from the two victims. As she did with other tests, Cotton reviewed a series of X-rays, pointing out where black slashes indicate strands of DNA.

Although the results were less conclusive than those for the bloodstains at the murder scene and in Simpson’s foyer, Cotton nevertheless said tests indicate that Nicole Simpson was a possible source of that blood; the results for Goldman showed that while the blood contained some of his markers, others were too faint to see and thus no conclusions could be reported.

Another blood mixture that prosecutors hope to introduce comes from the steering wheel of Simpson’s Bronco. That smear, they say, contains genetic material that could come from Simpson, as well as at least one of the victims and possibly from another source as well.

Two other mixtures will be the subject of testimony by the next expected witness in the trial, an expert from the California Department of Justice, which ran tests on other samples. Those two items involve what prosecutors say are mixtures of the blood of Simpson and the two victims--one set of stains from inside Simpson’s vehicle and another from the glove found at his estate.

The statistical significance of the blood mixtures is less overwhelming than that of other DNA tests, and prosecutors had sought to introduce them without accompanying statistical data, an approach that drew a vigorous defense objection and forced a hearing outside the jury’s presence.

After hearing from both sides, Ito ruled that the prosecution’s proposed approach was improper, and he ordered government lawyers to include the statistical significance of all their DNA “matches,” including the samples that appear to be a mixture of blood from more than one person.

That appeared to clear the way for prosecutors to proceed, but just before the jury was brought in, the defense mounted a last-ditch attempt to keep the panel from hearing about some of the DNA evidence. Ito rejected that effort, ruling in favor of prosecutors who said Cotton had established the foundation that they needed.

Results Told to Jury

When the jury entered, Ito apologized for the delay and mentioned in passing that he understood that jurors’ “Cinema 1 and Cinema 2” problem had been resolved, an apparent reference to the complaint of a dismissed juror that the panel’s movies were being apportioned in a way resented by some jurors. The members of the jury laughed loudly at Ito’s comment.

“Great,” said one. “Thank you.”

With the jury in the box and in good spirits, Clarke quickly turned to the presentation of the DNA test results that have been anticipated ever since prosecutors promised them during their opening statement in late January.

Cotton had spent two days schooling jurors on how DNA is used to identify the sources of biological samples. Wednesday, the panel was armed with that background as the scientist began culling through the reams of X-rays. The scientist held up a sample for the jurors, who each had their own, and showed them how to hold it and how to read it.

Then, with Clarke patiently leading her through the evidence, Cotton demonstrated where she saw the telltale black bands. Each time, she told the jury whether the results of the testing showed that blood could have come from either of the victims or from Simpson.

With the blood drop discovered at the murder scene and the drop from Simpson’s foyer, Cotton said the tests were unambiguous: Neither Nicole Simpson nor Goldman could have been the source of those drops, while Simpson could have been.

Conversely, the test on the socks showed another compelling result, she said: that the blood found there could not have come from O.J. Simpson or Goldman, but that it could have come from Nicole Simpson.

Throughout her testimony, Cotton mixed technical terms--all of which she carefully has defined for the jury this week--with common-sense observations. The procedure for conducting DNA tests is sensitive and in some ways highly technical, and the X-rays themselves are sometimes grainy or faint. Nevertheless, some of the results are plainly visible, and the findings are double-checked by a computer-imaging process, Cotton said.

Any time there was confusion, Cotton said, the results were double-checked by her and by at least one analyst, as well as by the computer.

Despite its enormous significance in the case, Cotton delivered her testimony in the same low-key tone that she and prosecutor Clarke have adopted since she took the stand, a style that struck some observers as underwhelming but that impressed others.

Said UCLA law professor Peter Arenella: “While Clarke elicited this incriminating evidence from Cotton in a methodical manner that might have eroded some of its dramatic impact, his questions and Cotton’s careful answers reinforced the message that this damning evidence can be trusted as the reliable product of a dispassionate scientific inquiry.”

Challenge for Defense

The DNA test results long have formed the bulwark of the prosecution’s case, and experts said that rebutting them forms the biggest challenge for Simpson’s defense team.

“It has this cumulative effect,” said Howard Coleman, president of a Seattle-based DNA lab, GeneLex Corp. “There’s just more and more DNA profiles, until it just becomes irrefutable. An alternative hypothesis becomes absurd.

“In this case,” Coleman added, “there is an avalanche of evidence. I know of no other case that has had this much testing.”

As he left court, however, lead Simpson trial lawyer Johnnie L. Cochran Jr. said he was not concerned about Cotton’s testimony and the DNA results that she is presenting.

“I heard some evidence, but I think you’ve got to hear all the evidence and you’ll get a better sense of it,” said Cochran, who described the interpretation of the DNA results as “very subjective.”

“We’re going to deal with it on cross-examination and our witnesses,” he added.

Against the advice of some defense team members, the Simpson team elected to forgo an extensive pretrial hearing on the admissibility of the DNA evidence, a decision that limits their ability to challenge the evidence at this stage. But the defense has reserved the right to challenge many aspects of the DNA test results and has mounted a number of other attacks on the scientific evidence, most provocatively by suggesting that at least some of it was planted by police.

The defense has offered no direct evidence of that, but it has suggested that police kept a vial of Simpson’s blood overnight and used it to stain some items. Simpson’s lawyers also have argued that an erroneous television news report offers circumstantial evidence of tampering with the socks.

The television report asserted that DNA tests of the socks had been performed in September and had pointed to Nicole Simpson as the likely source of that blood. In fact, only conventional tests had been performed at that time, and the defense has argued that the television report predicted the DNA results because the reporter’s sources were involved in planting the evidence. The reporter is on the defense witness list.

Bolstering that theory, the defense wants to show that there are traces of preservative on the bloody socks. That preservative is not found inside the human body but is added to blood when drawn. If present on the socks, the preservative could support defense allegations that a blood vial was used to stain them sometime after they were seized.

The FBI tested the socks and other stains and concluded that there was no evidence of the preservative, which is used commercially, not just in blood vials. But defense sources told The Times last month that tests of the socks and of blood found on the back gate of Nicole Simpson’s condominium did reveal some faint traces of the substance--previewing yet another dispute between experts.

On Wednesday, Deputy Dist. Atty. Rockne Harmon seemed to confirm that brewing battle during a hearing outside the jury’s presence. Harmon read the FBI’s conclusion that the preservative was not present, but, in response to a question from Ito, added: “There’s no question that there’s a flicker of hope (for the defense) that there could be something in there.”

Simpson smiled broadly at that admission.

Once the jury was gone for the day, Ito cleared the decks of two lingering issues in the case, denying motions by each side for sanctions against the other. He did not rule on another longstanding issue, the prosecution’s desire to put Simpson’s friend and lawyer Robert Kardashian on the stand.

Prosecutors want Kardashian to testify about his handling of one of Simpson’s bags. In a declaration filed Wednesday, Kardashian said he never opened that bag, but prosecutors have so far been unwilling to accept that declaration as true. They want the chance to question him under oath.

Times legal affairs writer Henry Weinstein contributed to this article.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

DNA Profiling

When DNA from a crime scene is profiled, the result for each sample is a series of bands that looks like a supermarket bar code. Shown below are profiles for blood from the three principals, the crime scene and O. J. Simpson home. The profile for O.J. Simpson’s socks is consistent with Nicole Simpson’s blood, profiles from the foyer and the walkway are consistent with O.J. Simpson’s blood, and the profile from the boot is consistent with a mixture of Nicole Simpson’s and Ronald Goldman’s blood. In the case of the boot, some of Goldman’s bands are either too faint to see or have been obscured by Nicole’s bands.

O.J. Simpson

Nicole Simpson

Ronald Goldman

Sock at Rockingham

Rockingham foyer

Bundy walkway

Goldman’s boot

Researched by THOMAS H. MAUGH II / Los Angeles Times