BODY: After 15 years in prison for a rape and murder he insists he didn't commit, Anselm Holman thought DNA testing would finally set him free.

Instead, a blunder by the Illinois State Police crime laboratory not only threatens to cost Holman a chance to prove his innocence, but almost certainly will bring additional scrutiny by defense attorneys who say the lab has made repeated mistakes in recent years.

In the Holman case, a forensic scientist at the crime lab committed what forensic scientists call an extraordinary error: contaminating a semen smear on a microscope slide by somehow transferring his own DNA into the evidence. The situation has confounded experts, who note that one of the nation's premier crime labs, based in Connecticut, even tried and failed in an experiment to deliberately contaminate DNA evidence by sneezing into a sample and by putting hair, blood and skin cells into it.

It's unclear how the contamination in this case occurred, but Holman's lawyers say the scientist who performed the test told them he was not wearing gloves. That, according to experts, violates fundamental laboratory procedures for such testing.

For Holman, the error by the Illinois crime lab caps an odyssey through the criminal justice system that he claims is marked by allegedly illegal police conduct and a bewildering omission by the attorney who handled Holman's initial appeal.

While Holman's co-defendant won his freedom when the Illinois Appellate Court ruled that Chicago police arrested him illegally, Holman's attorney failed to raise that claim on appeal even though the circumstances of the two defendants' arrests were so similar the appeals court expressed wonder that the issue hadn't been raised.

"It's like he lives under this dark cloud like that character in Peanuts," said Tom Betten, one of Holman's current attorneys. "It's all dumped on Anselm's head."

Prosecutors acknowledge the mistake occurred but say they will continue to assume Holman is guilty in the absence of evidence that exonerates him.

Holman, now 32, was one of the first inmates in Illinois to take advantage of a new state law that took effect last year granting certain defendants who were convicted when DNA testing hadn't been developed the opportunity to have it done now.

He was arrested in 1984 at the age of 17 and charged with the rape and murder of Mary Brackenridge, a 75-year-old woman killed in her apartment on the city's West Side. He was convicted the next year based on a statement he gave to detectives in which he allegedly admitted committing the crime.

But Holman, serving a life sentence without the possibility of parole, testified in a pretrial hearing that he provided a false confession because police were beating him--a claim the officers have denied.

Holman's attorneys now plan to ask a Cook County Circuit Court judge to allow them to have the evidence recovered from the victim tested by an independent laboratory. Still, they fear the contamination has made it impossible to discern the rapist's identity from the small amount of physical evidence remaining in the case.

According to a representative of the Cook County state's attorney's office, the state's test identified DNA from only two people--the victim and the analyst. The analyst's DNA was compared with the test result after officials excluded at least two other possible suspects in the case as the source of the semen, lawyers involved with the case said.

Ralph Ruebner, a professor at John Marshall Law School, has been representing Holman during the last 11 years of his appeal. Ruebner believes the error in this case could also have a ripple effect on other DNA cases handled by the state lab, whose employees have come under fire for what critics say is shoddy work with such forensic testing as hair comparison and blood-typing evidence.

"Imagine what this will do for other individuals either awaiting trial or already convicted, where there's an open admission of contamination in the state lab," Ruebner said. "This could open up an incredible dilemma for prosecutors in Illinois."

Other legal experts said the effect would likely be more limited to cases handled by the analyst who contaminated the evidence.

Moses Schanfield, chief of a forensic genetics lab in Denver, said he had never heard of a case in which a DNA sample had been contaminated by the analyst's own DNA.

"This shouldn't happen," Schanfield said. "It should cast a good deal of questions about the people doing the profile as well as the laboratory."

Added John Gerdes, a Denver scientist who testified for the defense in the O.J. Simpson criminal trial: "I can't believe that he didn't wear gloves. And it's not only to protect yourself, but also to prevent contamination. That's absolutely standard. It's unbelievable."

Crime lab officials and Cook County prosecutors disclosed the contamination error to Holman's attorneys at a meeting two weeks ago.

"They were very embarrassed; they were ashen," Betten said. "It was a dark day."

Crime lab officials couldn't say how it happened, but the forensic scientist who performed the tests, Aaron Small, offered a possible explanation during that meeting, the lawyers said.

"I said to him, 'How did your DNA get into this evidence?' " Ruebner said. "And he said, 'I handled the slide without gloves. I may have touched my nose and then the slide.' He did not believe he was bleeding at any time when he handled the slide, but he thought perhaps he may have had a small cut that could not be seen or wasn't bleeding due to the roughness of the slide."

Small, 29, has worked for the state since 1992, according to state records. He declined comment Monday, referring questions to a supervisor.

James Kearney, laboratory director for the Illinois State Police Forensic Science Center in Chicago, declined to talk about the specifics of the Holman case because it's still under appeal. But he said he does not believe this incident reflects on the lab's overall competence.

"We've worked dozens of cases, into the hundreds of cases, and not seen contamination," Kearney said. "Does that mean there might be a case out there where contamination might occur? Yes, I think that's possible."

Kearney said he doesn't know of any other case where contamination like this has occurred in the Illinois lab.

Richie Cole, then 16, was arrested along with Holman and likewise convicted of taking part in the crime. But Cole's conviction was thrown out three years later when the Illinois Appellate Court found that his confession, which Cole claimed was coerced, should have been suppressed because police had arrested him without probable cause. Cole was not retried.

In reversing Cole's conviction, the appellate court noted that Holman "might also have a colorable" claim of unlawful arrest, but said that was waived since Holman's attorney hadn't raised it on appeal.

Holman's former attorney ultimately filed an affidavit saying that a claim of unlawful arrest had been considered but for whatever reason he didn't think it would prevail.

Holman's appeals have subsequently been denied.