Marshall Frank, a cop for 30 years, supervised 3,000 homicide investigations in Miami-Dade County. He retired in 1990, giving up his gold badge and .38 revolver for the comfortable life of a novelist in Maggie Valley, N.C.

His life is not so comfortable anymore. He is again caught up in a homicide investigation. Time is running out. A life hangs in the balance. And he now questions his faith and belief in the criminal justice system.

Frank, 64, a detective captain who made a career of sending killers to prison, is certain that a Florida Death Row inmate is an innocent man.

The inmate once was a rookie cop, and he is condemned to die for the rape and murder of a little girl, supposedly committed while he was on duty.

''How this could happen is baffling,'' Frank says. ''I'm simply amazed.'' He stumbled upon the case by chance. Researching a scene for his fifth novel, Frank wanted details about daily life on Death Row. He went to the source. He wrote to 15 inmates. Ten responded; all, not unexpectedly, claimed to be innocent. Not so unusual, he thought. What was unusual was the response from James Aren Duckett, 45.

''Something just gave me a gut feeling,'' Frank says.

Frank looked into the case, then looked some more, then launched his own investigation, slowly and methodically examining the evidence. ``What I found chilled me to the bone.''

His conclusion: ''Jim Duckett is innocent. He didn't do it.'' Frank couldn't stop thinking about it. ``Consider what it would be like if someone came and took your freedom away, not for a day or a couple of days, but for more than 5,000 days. Imagine. The prime of your life gone forever. Your family, your kids, your career and your dignity. That's what has happened to this man.''

MIAMI EXPERIENCE

Marshall Frank worked as a crack investigator for a big-city police department through Miami's toughest years of riots, cocaine wars, the Mariel boatlift and record years of homicides.

James Aren Duckett lived as a small-town policeman. He was a rookie in a five-man department in the tiny blue-collar town of Mascotte in Central Florida's Lake County -- until he was accused of rape and murder. He has been on Death Row since 1988.

Marshall Frank, who pieced together the jigsaw puzzle that was the police beating death of insurance salesman Arthur McDuffie in 1979 and wrote the rules that detectives use to investigate murders, is not alone in his conclusion.

Former Mascotte Police Chief Michael Brady, Duckett's boss at the time of the crime, insists Duckett is innocent and was framed.

So does the town's then-mayor, Josh Thomas. ''Jim Duckett never killed that girl,'' Thomas says. ``Everybody up here knows he didn't do it.''

Jeanne Bragg, a former beautician and citrus inspector, a total stranger like Frank, also became convinced that justice had miscarried. Untrained as an investigator or a writer, she became both and published her own book in 2001: The Truth Shall Set Him Free. So far, it hasn't.

Newspapers also questioned Duckett's guilt. Under the headline ''Maybe Convicted Officer Isn't Guilty,'' Lauren Ritchie, Lake County editor for The Orlando Sentinel, wrote in November 1997: ``Is it possible that James Duckett could be innocent? I think it may be.''

Another pro-bono ''total stranger,'' investigator Ron Hill, took up the cause on his own, and is writing a book, The Convenient Suspect.

Duckett remains on Death Row, awaiting a ruling from an appeal to the Florida Supreme Court. Frank insists that the chances that Duckett committed the crime are ''zero.'' But outside opinions don't count for much before the court.

Life as James Duckett knew it ended forever on Monday, May 11, 1987, when he donned his uniform and went to work on the 7 p.m. to 7 a.m. shift. There is not much to patrol in Mascotte (pop. 1,795), which is 20 minutes south of Leesburg in Lake County. State Road 50 is the town's main street. Its citizenry is made up mostly of Mexican labor, farmers and poor whites. The town's one bar and three convenience stores serve the populace quite adequately.

Duckett, then 29, grew up in Central Florida. He married his childhood sweetheart, Carla, and they had two little boys. When he was laid off because of a slowdown in the economy, Duckett wanted a more stable job and decided on a law-enforcement career. He hoped to eventually become a game warden.

He'd been on the job for just seven months that Monday when sometime after 10 p.m. Dorothy McAbee gave her daughter Teresa, an 11-year-old schoolgirl, 25 cents to purchase a pencil at the nearby Circle K convenience store. The fifth-grader insisted she needed it to do her homework.

The Circle K is just 400 feet from the tiny, rundown converted garage Teresa shared with her mother, her mother's occasional boyfriends, her mother's sister Shirley Fernandez, and Shirley's husband and their two children. Teresa was a fixture at the Circle K. She hung out there most evenings, making friends, socializing and playing video games. Her mother had already picked her up there and brought her home once that night.

Duckett was working radar across from the Circle K after 10 p.m. when he saw young Teresa McAbee huddled behind a trash bin with a Mexican teenager named Salvador Calisto. Suspicious, he spoke with the store clerk. She voiced her concerns, saying that the girl, so mature for her age that she shared the same size shoes and clothes as her mother, was frequently there late at night laughing and talking with strangers, men who gave her quarters to play the games.

Duckett stepped outside, separated the youngsters for questioning, took notes, told Calisto, 16, that he had no business with a girl of 11, reminded them of a 10:30 p.m. curfew for juveniles, and sent them both home. He also spoke to Calisto's uncle, who picked him up. Because Teresa lived so close to the store, Duckett did not drive her home. He said he last saw her walking toward her residence.

At midnight, the mother, Dorothy McAbee, called police to report that Teresa had not returned home. Duckett quickly realized that she was the same girl he had sent home, he said. This was his first missing person report. He called Chief Brady at home at 1 a.m. to be sure that he handled it properly. He wrote the reports, went to the McAbee home for a photo of Teresa, made copies at headquarters, notified other law-enforcement agencies, then went off duty at 7 a.m.

Mascotte officers normally washed their patrol cars at the end of their shifts, but it had been a long night, and Duckett did not.

Shortly after 9 a.m., a fisherman at Knight Lake, about a quarter of a mile from where Teresa was last seen, spotted what he thought was a mannequin. It was the body of Teresa McAbee, face down in shallow water at the lake's edge.

Fully dressed in blue jeans, a tan and white striped shirt, socks and sneakers, the schoolgirl had been sexually abused, strangled and drowned. Chief Brady turned the investigation over to the larger Lake County (pop. 152,115) sheriff's department and called in Duckett from home that afternoon to assist.

Lake County sheriff's detectives Rocky Harris and Chuck Johnson immediately focused on the last person to see the girl alive, small-town police officer Jim Duckett. The victim weighed 83 pounds. Duckett was six feet tall and weighed 225 pounds.

Chief Brady asked why they suspected the officer. He quotes Johnson's response: ''I could tell the minute I shook hands with Duckett that he killed that girl.'' Brady, now a North Florida corrections officer, recalls that he retorted, ''Well, then, next time we have a killing, we'll just line up everybody in Lake County so you can shake their hands and tell us who the murderer is.'' Johnson, now an attorney, denies that he made the comment.

Brady said the detectives appeared to eliminate Duckett as a suspect that first day, but after conferring with Sheriff Noel E. Griffin, they immediately refocused on the rookie cop as their suspect.

Brady says the sheriff told him that the way you solve a homicide is to find a suspect, ``then build a case around him.''

Brady said, ``The way I learned it is, you let the evidence lead you to a suspect.''

Griffin had troubles of his own at that time. As he faced reelection, he'd received a lot of bad press. He'd been accused of botching another murder case involving the slaying of a rancher and his foreman, and was under fire about items missing from the evidence locker. A judge had declared that the sheriff's testimony could not be believed.

Frank wonders if the sheriff, concerned about public image, sent his detectives on a rush to judgment. Duckett says he was asked to submit to a polygraph test. He said ''yes'' without qualification when first questioned. But no test was given.

About five weeks later, after hours of interrogation, he was asked again. Weary and emotionally upset, he agreed, but considering the circumstances, wanted to consult an attorney. Duckett was worried, he said, because the test was to be administered by Lake County sheriff's Capt. Jim Horner, one of his accusers.

''An accuser is not the independent examiner a good polygraph requires,'' said Frank. ``Personally, if you asked me if I killed Abraham Lincoln, I would not take a polygraph. As a detective, I used the polygraph as an investigative tool, and I understand the process quite well. The machine does not detect lies, it detects stress, and persons react differently. My method was to use the polygraph as an intimidation device, which often worked in securing confessions. But does a polygraph detect a lie on a chart? No.''

No test was ever given. The case went to trial April 26, 1988, and the prosecution impressed the jurors. Prosecutors Tom Hogan and Steve Hurm produced palm prints of the victim on the officer's cruiser, tire tracks at the scene, a hair identification, and a witness who said she saw the victim get into the officer's car.

BELATED ANALYSIS

Fifteen years after the crime, Marshall Frank began to dissect what happened.

The state claimed that Duckett assaulted the girl on the hood of the police cruiser -- where Teresa's palm prints were found, fingers pointing outward. ''As if she was sitting,'' Frank says. Teresa probably sat on the police car's hood while Duckett's back was turned to question Salvador Calisto and the uncle who came for him, Frank thinks.

Duckett could have lied and said she did, but the truth is that he never actually saw Teresa sit on his car. Frank notes from his own experience that if she was assaulted on the hood of the car as the prosecutor theorized, ``impressions from other parts of her bare body should have developed during the testing process, i.e., buttocks, arms, legs. They did not.''

The state asserted that tire tracks at the crime scene matched Duckett's patrol car. The horseshoe-shaped dirt road that abuts Knight Lake is in a wooded area less than 500 yards from Teresa's house.

Crime-scene technicians allegedly took a cast of tire tracks from a mud hole on one side of the road's curve, beyond where the body was found. Although technicians stated they were the same brand and pattern as the tires on Duckett's patrol car, the match was not positive.

When Chief Brady and another officer first heard about the tire casts, they returned to the scene. They saw no signs of casting at the mud hole, but did find casting marks on the dirt road near where the body was found.

Significantly, another Mascotte police car with the same brand of tires had responded there first. Duckett also parked there that afternoon. If casts were taken from the area Chief Brady noted, those cars belonged there. And if Duckett's car had crossed the mud hole, mud would have been found on his tires and wheel well. None was.

The prosecution claimed that a pubic hair found in the victim's panties belonged to James Duckett. But the hair, according to Frank, had no root, which made DNA identification impossible.

TWICE, NO MATCH

Initially, Lake County investigators sent the hair and samples from Duckett to the Florida Department of Law Enforcement lab. FDLE expert Deborah Steger testified there was no match. The Lake County detectives then sent the same evidence and samples to a private lab, Lifecode in New York. Again, no match.

''Somewhere in their shopping spree,'' Frank says, ''the Lake County detectives heard about FBI agent Mike Malone,'' an expert analyst for hairs and fiber. Five months later, after taking more samples from Duckett, Malone made a match. That forensic evidence sealed Duckett's fate.

Marshall Frank contends that the fact that Malone even accepted the case is suspect because of the FBI's long-standing policy of not accepting forensic evidence for analysis if another certified crime lab has already examined it.

Malone had a reputation for being a dream witness for the prosecution. Although differing with other analysts, he nailed defendants in cases around the nation. He testified that Duckett's hair had ''exactly the same characteristics'' and was ''completely indistinguishable'' from the hair found in the victim's panties.

But Malone's reputation, splendid at the time of conviction, is now stained in disgrace. ''He was at the center of a crime-lab FBI scandal in which he had allegedly given incorrect or false testimony in case after case,'' Frank says. He is cited in ''a devastating book by John F. Kelly and Philip K. Wearne, Tainting Evidence: Inside the Scandals at the FBI Lab.'' Malone is now retired.

In the Duckett case, Malone's conclusion was refuted not only by the FDLE's Deborah Steger and the New York lab, but by Peter DeForest, professor of criminalistics at John Jay College.

And not only did DeForest disagree with Malone, but he declared: ''There was no match with the original samples taken from Duckett. However, Malone made a match with a sample they had taken six months later. It suggested to me that somebody had switched something. Certainly, something did not smell right.'' But he wasn't called to testify.

If DeForest is correct, Frank says, then someone in the police agency must have discarded the evidence hair from the victim's panties, replacing it with Duckett's hair.

Does Frank believe that happened? ``It would appear so. It could have been anyone -- someone in the police department or Malone himself.''

COMING MONDAY: A claim of questionable testimony and withheld evidence.