On a dreary, freezing January day here nearly 18 years ago, a 20-year-old woman opened her door to a man who inexplicably and violently stabbed her more than 30 times. Within a couple of weeks, the police charged an unemployed construction worker with attempted murder.

Harold "Gene" Weatherly, then 25, maintained his innocence through numerous voluntary interrogations, a trial in which forensic evidence nailed him, and two parole hearings in which his refusal to admit guilt cost him early release. He served 15 years in prison.

He was sure, he says now, that one day the truth would rescue him, the truth that -- contrary to the damning testimony of now disgraced police chemist Joyce Gilchrist -- he was never in the victim's home. The truth, the FBI declared this year, was that the fibers on his tennis shoes did not match those from the crime scene, as she had testified.

Weatherly is just one of hundreds of inmates -- former and current -- caught up in arguably the biggest law enforcement scandal in Oklahoma history. Gilchrist, who was fired in September, has been accused of egregious misrepresentations of forensic evidence over two decades. Already, a reexamination of her work has freed a convicted rapist and a death row inmate, overturned a death sentence, and called into question the evidence used to execute a man last year.

Gilchrist, through her lawyer, declined a request for an interview. She has said she has done no wrong.

Separate state and federal investigations have spent months scrutinizing Gilchrist's work in more than 1,200 felony cases, and $650,000 has been appropriated to perform DNA analysis, which was unavailable in the 1980s, on many of her cases.

And she is not alone. As DNA analysis has freed dozens of convicts, with hundreds more cases pending, it has also raised questions about the scientists who helped convict them. In May, the National Association of Criminal Defense Lawyers appointed a forensic task force to study the issue.

In the most high-profile incidents nationally, at least 10 convictions have been overturned in Illinois, West Virginia and Texas because of the work of two criminal scientists. The 1987 testimony of Illinois forensic scientist Pamela Fish in a rape and murder case is under review now because recent DNA testing showed semen recovered from the victim did not match any of the four men convicted of the crime. And in West Virginia, a jury deadlocked in September when the state tried Fred Zain for fabricating blood-test findings after convictions that relied on his testimony were overturned.

Oklahoma investigators are almost done with a preliminary review of the Gilchrist cases and have flagged about 165 that merit further review. Still, state officials say it will take at least a year to untangle a mess that has eroded confidence in the legal process and stretched the nerves and resources of law enforcement officials. Critical evidence is missing or lost in some of the 20-year-old cases, trial transcripts are floating somewhere around the court system, and witnesses have moved or died.

But the most sensitive aspect of the investigation is whether the state of Oklahoma, relying on Gilchrist, may have executed an innocent man -- or someone who would have been sentenced to life without her critical testimony.

Twenty-three capital cases have been identified in which Gilchrist provided testimony. Of those, 11 convicted murderers have already been put to death, and 12 sit on death row. State officials insist no one has been wrongly executed.

Last month, a federal grand jury subpoenaed all evidence from 10 murder cases in which Gilchrist testified to determine whether the defendants' civil rights were violated. Nine of the cases have already resulted in executions; the 10th is serving life without parole.

"Whether it was intentional or just negligence, the fact is that her testimony was used to secure death sentences in cases where these people might have been sentenced to life," said James Bednar, executive director of the Oklahoma Indigent Defense System (OIDS), a state agency spearheading the DNA testing. "If just one of these people would have been sentenced to life without her testimony, the entire criminal justice system has been undermined."

Gilchrist's Rise and Fall

What seems baffling in hindsight is how Joyce Gilchrist survived for so long. Questions had been raised about her work for over a decade -- by judges, by defense attorneys and by her own peers.

Oklahoma County's new District Attorney C. Wesley Lane II, who took over in July, struggled to explain why she remained in her position. True, he said, defense lawyers were always criticizing her, "but they take shots at everybody." In any event, he said he is committed to making things right.

The daughter of a butcher and a factory worker, Gilchrist obtained a degree in forensic science from the University of Central Oklahoma in 1980. By then she was already working in the Oklahoma City police crime lab, attracted by the mysteries of crime work. "It's up to you to recognize, to listen to what the crime scene is trying to tell you, put it all back together and make a picture," she once said in an interview.

From the beginning, she seemed to get the results the prosecution wanted. She was an articulate and forceful witness, and prosecutors -- particularly the legendary Oklahoma County District Attorney Bob Macy -- came to rely heavily on her. (Macy, 70, resigned unexpectedly in June, as the Gilchrist scandal escalated, saying he wanted to spend more time with his family.)

But in 1987, a Kansas City, Mo., police chemist wrote a scathing letter to the Southwestern Association of Forensic Scientists at the behest of Oklahoma defense lawyers, complaining that Gilchrist rendered "scientific opinions from the witness stand which in effect positively identify the defendant based on the slightest bit of circumstantial evidence."

In a recent interview, John T. Wilson said he took the unusual step of publicly criticizing a colleague after several Oklahoma defense attorneys asked him to review her testimony in preliminary hearings. He ultimately testified against her for the defense in three murder cases.

"I got major heat" for testifying, said Wilson, the chief criminologist for the Kansas City police crime laboratory. "But I felt I had an ethical obligation. When I read the transcripts and saw what she was saying, I was really shocked. She was positively identifying hair and there's no way in the world you can do that without DNA."

The regional group concluded after an investigation that Gilchrist violated the organization's code of ethics, and formally censured her.

Yet back in Oklahoma she continued to receive glowing performance evaluations and to testify, acquiring the nickname "Black Magic" from the police because of her success. "It was in reference to a homicide case where the defense attorney referred to me in his closing argument as a sorcerer . . . and stated that I seemed to be able to do things with evidence that nobody else was able to do," she told CBS's "60 Minutes II" in May.

A year after Wilson wrote his letter, the Oklahoma Criminal Court of Appeals overturned the murder conviction of Curtis Edward McCarty because Gilchrist gave "personal opinions beyond the scope of scientific capabilities." McCarty was reconvicted and sentenced to death; his case is now one of three death row cases identified by the state for further testing.

The next year, 1989, the same court overturned another murder conviction and ordered a new trial for James Lucas Abels, saying that Gilchrist had improperly testified, based on hair analysis, that Abels had been "in very close and possibly even violent contact" with the victim.

A year after that, Gilchrist was promoted to supervisor.

It was not until August 1999, when a respected federal judge in Oklahoma City harshly rebuked Gilchrist, that things began to unravel for her. U.S. District Judge Ralph Thompson bluntly labeled as "untrue" her testimony that semen samples in a rape and murder case were "inconclusive" -- when, he said, Gilchrist knew for a fact that the sperm could not be from the defendant. Thompson overturned the rape conviction of Alfred Brian Mitchell. (He left the murder conviction intact, but the death sentence was recently overturned by the 10th Circuit Court of Appeals.)

Stung by Thompson's remarks and mounting criticism, police removed Gilchrist from the lab the following March, and assigned her to an administrative position. Seven months later, in October 2000, she was expelled from the Association of Crime Scene Reconstruction for giving testimony that misrepresented the evidence.

"She was a hack for the prosecution," said Jamie Pybas, who supervises the DNA forensic testing for OIDS.

"It was common knowledge within the defense bar and should have been to the DA's office that she was incompetent and malicious," said attorney David Autry, who has represented a number of people he says were railroaded by Gilchrist. "She survived because she made close cases for the prosecutors and secured convictions in particularly heinous crimes."

Autry and other lawyers charge that Gilchrist went way beyond the accepted scientific practices of her time. "She would come up with hair analysis that few could refute because the technology was not available," said Autry. Oklahoma City public defender Robert Ravitz said Gilchrist's analysis often went unchallenged at trial because defendants did not have the funds to conduct independent examinations.

Scathing Police Report

Gilchrist's free fall started in January with a scathing internal police report, which was clearly in the works for months. It criticized her for everything from sloppy handling of evidence to incompetent management of the laboratory. About the same time, serious questions began to emerge about Gilchrist's role in the 1986 rape conviction of Jeffrey Todd Pierce. The police department asked the FBI to examine eight of her more controversial cases.

A month later, she was placed on administrative leave. Today, she could face a myriad of state and federal charges, the gravity of which will depend on whether she is found to have lied intentionally or was simply incompetent.

The FBI found that in five of the eight cases she had either erred in her analysis or overstated her conclusions. Gilchrist gave testimony, the FBI said, that "went beyond the acceptable limits of forensic science." Her laboratory notes "were often incomplete or inadequate to support the conclusions reached."

With specific reference to Pierce, the FBI stated that Gilchrist's own analysis did not support her primary conclusions that 28 scalp hairs and three pubic hairs were "microscopically consistent" with Pierce's hair. A month later, when DNA testing of semen exonerated him, Pierce was released from prison after having served 15 years of a 65-year term.

A 24-year-old father of young twin boys at the time of his conviction, Pierce always maintained his innocence. After his conviction, he divorced his wife and cut off contact with the boys because he did not want them growing up knowing their father was in jail. By the time he was released, he had lost all his jail privileges because he refused to enter a sex-offender treatment program.

He is now reunited with his sons and ex-wife in Michigan -- although they haven't remarried yet. "I blame most of what happened to Jeff on Gilchrist," said his brother, Gary. "I don't know how she lives with herself."

Legally speaking, Pierce is considered one of the lucky ones because his name was cleared before he completed his sentence and his basic freedoms -- like the right to vote -- have been restored. He also can make a stronger case that his rights were violated should he decide to sue the state, which he will likely do, Gary Pierce said.

Many of the others against whom Gilchrist testified, like Gene Weatherly, have already done their time and have little recourse. Only a gubernatorial pardon can clear their names.

The Death Row Cases

As the Gilchrist investigation lumbers past its seventh month, the state multi-agency task force has agreed to test only three of the 12 current death row cases connected to Gilchrist -- and none of the 11 in which the perpetrators have already been executed. (A few additional death row cases that were handled by another chemist who worked for Gilchrist are also being reviewed.)

The Oklahoma Indigent Defense System, though, wants to conduct forensic testing on several additional Gilchrist death row cases, and seven of the 11 individuals already executed -- but has met resistance from state Attorney General Drew Edmondson.

Edmondson said in an interview that he does not want to test every capital case, maintaining that Gilchrist's testimony was not a definitive factor in most of them. "We looked at each case critically and assumed that no forensic evidence was involved, and asked, 'Is there still sufficient evidence to convict?' " Edmondson said. "Based on that, I am personally satisfied that no innocent person was executed, and that we are examining the appropriate death row cases."

Everyone seems to agree that in most of the 23 capital cases involving Gilchrist, the defendants have demonstrable culpability. But that is not the point, say defense lawyers, if the conviction and sentences were obtained fraudulently.

"It's very simple," said Jack Dempsey Pointer, president of the Oklahoma Criminal Defense Lawyers Association. "If we're going to invoke the highest penalty that society can impose, we better get it right."

So argues the family of Mark Fowler, executed in January for the 1985 murder of three grocery store clerks in a back room during a robbery. Fowler admitted being part of the robbery, but denied playing a role in the murders. He said he was outside in the getaway car when his accomplice shot and stabbed the victims.

But Gilchrist asserted that hairs found on a victim and on a murder weapon were consistent with Fowler's. The state has refused to conduct a DNA test on the hairs.

The defense bar -- and even some state attorneys involved in the investigation -- believe Edmondson has a conflict of interest.

"The attorney general has for years defended against these appeals, arguing that there is nothing wrong with the testing, while he may have known it was shaky," said Steve Presson, who heads the Oklahoma Coalition to Abolish the Death Penalty. "He has an interest in preserving these convictions and sentences and therefore should not be involved in deciding which cases are tested."

Edmondson says he does not believe he has a conflict during this stage of the investigation, but vowed to appoint a special prosecutor if investigators determine a crime has been committed by law enforcement officials such as Gilchrist.

Edmondson did concede, however, that one additional case may merit more testing: that of a man executed last year.

Malcolm Rent Johnson was put to death in January 2000 for the 1981 rape and murder of 76-year-old Ura Alma Thompson in Oklahoma City. He maintained his innocence until the end. Gilchrist testified on hair, fiber and semen stains. Most significantly, she said that semen found on a bedspread and a pillow case in the victim's bedroom was consistent with Johnson's blood type.

But a private attorney, Doug Parr, who took up Johnson's cause after the Gilchrist scandal broke, has been challenging the state and the police to reexamine the forensic evidence.

Over the summer, he sued the police department for the records to no avail. But last July, in a startling development, the police lab stated in a memo obtained by media that it had recently reexamined the original slides purportedly containing the sperm and found no sperm there -- contrary to Gilchrist's claims 19 years ago.

While the findings do not exonerate Johnson, says Parr, "it indicates that she gave false testimony at the trial."

During Johnson's trial, then-District Attorney Bob Macy argued that Gilchrist's forensic testimony was "damning, it's condemning, it's conclusive." But today the state is arguing just the opposite. Edmondson insists that Johnson -- who had pleaded guilty to rape a few years earlier -- would have been convicted anyway because the victim's apartment key, watch and other items were found at his apartment. Johnson, who was considered borderline retarded, had stated that someone else gave him the property.

"I just can't believe in my wildest dreams that a jury, even back then, would give someone the death penalty based on that kind of flimsy evidence" without Gilchrist's forensic testimony, said Ravitz, the public defender who represented Johnson at trial. It was Gilchrist, Ravitz contended, who placed Johnson in the victim's apartment.

The next step would be to test the sperm on the bedspread and pillow case for DNA, which Edmondson said he would agree to. But that has been put on hold because federal investigators have confiscated all the evidence as part of the grand jury investigation.

Weatherly's Ordeal

Gene Weatherly, 43, knows now that he was a sitting duck for the police in 1984. At 25, he was already an unemployed, divorced father of two who had had at least two brushes with the law as a juvenile.

Without a lawyer, Weatherly cooperated with police, giving photographs, hair samples and interviews. He produced three alibi witnesses who said he was cleaning out a shed at the time of the attack. But the police rapidly built a circumstantial case. He agreed to a polygraph, which, according to news reports, showed indications that he was being deceptive.

In addition, said a prosecutor recently, "the composite sketch looked like Gene sat for it."

And then there was Gilchrist's testimony. "My opinion is that the person wearing that tennis shoe had to have been associated or had to have been in the home of [the victim] either during the crime or after the crime," Gilchrist stated at Weatherly's May 1984 trial. He was convicted of attempted murder.

Years later, Weatherly gained access to a police report that referred to identifiable bloody fingerprints at the scene -- potentially exculpatory evidence -- that were never given to his lawyers. Today, they are nowhere to be found. And earlier this year, the FBI retested the fibers in his case as part of the Gilchrist investigation. "None of the synthetic fibers" on his shoes was a match, the report stated.

"The report essentially exonerated him and there was not a thing he could do about it," Autry said. Unless the government acknowledges that it made an error, as it did in the Pierce case, it would be virtually impossible for him to successfully sue, legal experts say.

Today family photographs dominate the stark walls and shelves of Weatherly's small house in Hobart in western Oklahoma. But his pictorial family history seems to begin just a few years ago, at age 40. The other years are hidden between the pages of a brown photo album that documents his 15 years in jail through awkward family visits a few times a year.

He met a woman toward the end of his sentence, and they married a few months after his release in 1998. She just gave birth to their second child. He landed a decent job at a factory making about $25,000 a year.

But inside the little yellow A-frame with peeling paint, Weatherly is not at peace. Piles of papers and files cover the dining table, as he obsessively explains his case to lawyers and reporters and investigators.

After years of fighting Weatherly's appeals and claims of innocence, the state has taken a more open-minded public posture. New District Attorney Wes Lane said in an interview that he would support a pardon if Weatherly can present a convincing and comprehensive argument that he is innocent.

Weatherly is slightly buoyed by this development -- but he won't yet allow himself to relax. "Somehow," he said, "I feel like I'll be dealing with this for the rest of my life."

Chemist Joyce Gilchrist was fired this year.Jeff Pierce, center, with aunt Louise Burris, left, and sister-in-law Esty Pierce, was released from prison after DNA tests refuted testimony by a police chemist.Jim Fowler and wife Ann at a family grave site. His son, Mark, was executed in January, based on what he believes was false testimony by Joyce Gilchrist.Gene Weatherly served 15 years in prison for a murder based on evidence the FBI now disputes. Police chemist Joyce Gilchrist, who was fired this year, could face a myriad of state and federal charges.