Reliability of Blood Sample Disputed : Simpson trial: Cochran says it may have deteriorated. Prosecution sources say defense claims were misleading.

O.J. Simpson’s lead trial attorney acknowledged Saturday that a blood sample he told the jury suggests another killer may have deteriorated by the time it was tested, but he said the same problem undermines the samples prosecutors have amassed against his client.

“If they start talking about the blood being degraded, then it casts doubt on everything else they have,” Johnnie L. Cochran Jr. said in an interview. “We didn’t make this up. . . . If they take the position that all the blood is degraded, we’ll wipe out all the results.”

Prosecutors have built their case largely on the results of blood samples from the crime scene as well as from Simpson’s car and home. DNA tests of those samples, they say, point to Simpson as the source of drops at the scene and show that the blood of both victims was in his car and at his house.

But prosecution sources have said that Cochran misstated the significance of blood samples recovered from beneath Nicole Brown Simpson’s fingernails and from her thigh. In his opening statement, Cochran said those samples showed a blood protein of type B, a type not present in O.J. Simpson or either of the victims.

Cochran’s comments rocked the trial, offering the first suggestion that physical evidence from the crime scene might clear O.J. Simpson of the June 12 murders, to which he has pleaded not guilty.

The implication of the blood test results, Cochran told the jury, was that someone other than Simpson had been at the scene. If true, that would cast grave doubt on the prosecution’s contention that Simpson was the lone killer of Ronald Lyle Goldman and Nicole Brown Simpson.

Cochran based his comments on a quote from a government document stating that the blood found beneath Nicole Simpson’s fingernails and on her thigh could not have come from O.J. Simpson or either victim. He displayed that quote for the jury, but he did not tell the panelists about another sentence from that report qualifying the one he read.

According to sources, that sentence states: “Nicole cannot be excluded as a source of the stain if the EAP type B observed on the items were degraded from A-type BA.”

EAP is scientific shorthand for erythrocyte acid phosphatase, an enzyme found in blood. The blood from Nicole Simpson’s thigh and under her fingernails was EAP type B, while she, Goldman and Simpson have a different EAP type.

A source close to the prosecution said that the other sentence undercuts Cochran’s point and makes it clear that the physical evidence does not point to another suspect.

In the interview, Cochran acknowledged that there might be a “question mark” about the blood on Nicole Simpson’s thigh, but he said there was “no question mark” about the blood underneath her fingernails. Prosecutors were not available Saturday to respond to that comment.

As Cochran worked Saturday to fine-tune the remaining portion of his opening statement--which was interrupted last week by an acrimonious debate over evidence sharing--the defense lawyer said a number of witnesses who came under fire from prosecutors last week are angered by their treatment. After the defense belatedly disclosed details about more than a dozen witnesses, prosecutors conducted a hasty investigation and said Cochran’s list included “heroin addicts, thieves, felons” and one “court-certified habitual liar.”

Specifically, Deputy Dist. Atty. Christopher A. Darden said one woman, Mary Ann Gerchas, had a history of writing bad checks and had been sued at least nine times. (A Times investigation found 34 civil cases filed against her in recent years.)

Darden also accused another of Cochran’s proposed witnesses, Ron Fishman, of ducking a government subpoena and said a third, Christian Reichart, was out for revenge against a former fiancee cooperating with the prosecution.

According to Cochran, Fishman has retained a lawyer and Gerchas has offered to take a polygraph test. Such tests generally are not admissible in court.

Cochran is expected to resume his opening statement when the trial reconvenes Monday. He declined to comment Saturday on what he expects to say in the remaining portion of his statement, but other defense sources said Cochran will develop the defense theory that police framed Simpson.

Meanwhile, Simpson prosecutor William Hodgman, 41, who complained of chest pains Wednesday and was hospitalized, is feeling better and is expected back at work within a week, said Suzanne Childs, spokeswoman for the district attorney’s office.

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