It's been almost 20 years since the crime — a farm wife shot to death in her bed, her husband critically wounded.

Fourteen years have passed since the conviction of a neighbor who was just 16 at the time of the attack. After that decision was overturned, Mark Woodworth was convicted again of murder. That was a decade ago now — and still folks in this farming community believe the wrong man is in prison.

For teachers, doctors, politicians, farmers — even for the sheriff — there's just too much room for doubt.

"I have concerns about this entire case," said Livingston County Sheriff Steve Cox, who took office in 2000 after defeating the former chief deputy who was in charge of the Woodworth investigation. "I wish I could find a clear-cut piece of evidence supporting either innocence or guilt."

A five-month examination of the case by The Associated Press suggests the doubts about who killed Catherine Robertson are not misplaced.

Evidence pointing to other possible suspects — a mystery fingerprint, the reported sighting of a suspicious vehicle — was discounted or not fully explored by investigators. Motives ascribed to Woodworth had little support, or none at all. A prosecutor suddenly dropped out of the case, to be replaced by an ambitious special prosecutor who would be accused of misconduct in another case, in which a convicted youth had to be released after years in prison.

Even jurors expressed doubts. Soon after Woodworth was sentenced to four consecutive life terms plus 15 years, members of the jury told the judge they'd been wrong and had given in to pressure. But their plea for reconsideration was silenced.

Woodworth insists he's innocent. Among those who agree is Phil Thompson, a former Missouri state trooper and police officer.

"In the 40 or so years I was involved in law enforcement," said Thompson, who worked as an investigator for Woodworth's defense, "there were only a handful of times I felt that justice wasn't done. And this was one of them."

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Cathy and Lyndel Robertson were asleep in their bedroom when the shooting started, just before midnight on Nov. 13, 1990.

The 41-year-old mother of five, shot twice in the head and chest, was dead. Her husband survived bullet wounds to his mouth, cheek, neck and shoulder.

Claude Woodworth, Mark's father, was one of the first to arrive at the hospital to check on his farming partner. They had moved together to Missouri in 1974 after attending high school near Quincy, Ill.

According to the elder Woodworth and several others, Robertson identified his oldest daughter's boyfriend as the likely shooter.

Brandon Thomure denied any involvement, but Robertson had ample reason to suspect him. The 16-year-old had punched Rochelle Robertson and vandalized her car, according to investigative reports. One friend told investigators that Thomure threatened his girlfriend with a gun. Another reported witnessing Thomure grabbing Rochelle Robertson's neck and vowing to choke her to death.

Rochelle Robertson learned she was pregnant just before her mother's death. She agreed to an abortion but worried about her parents' reaction. They already wanted the two to break up.

Rochelle obtained a restraining order after the shooting. "He has struck me in the past, and has made frequent harassing telephone phone calls to me since Nov. 1," she wrote in the Nov. 21 court petition. "He may have murdered my mother and attempted to kill my father."

At first, the 30-plus law officers from across north Missouri who descended upon Chillicothe focused on Thomure.

They swabbed his hands for gunpowder residue, and the test came back positive — though prosecutors would later minimize this evidence, saying too much time elapsed before the test.

Thomure had an alibi: He said he was asleep at home in Independence, 90 miles away. He had no car and usually relied on Rochelle for rides. His mother, stepfather and younger sister vouched for him.

Rochelle said she talked with him on the phone at about 10 p.m. after leaving work. But Thomure testified that he didn't wake up for any reason after going to bed hours earlier, and neither he nor his family members mentioned that phone call at trial or in interviews with investigators before Woodworth was charged.

Investigative records reviewed by the AP show that two women reported Thomure stashed a duffel bag in their car trunks while staying at their Chillicothe apartment after the Robertson shootings. Investigators found four .22-caliber shell casings, the type of ammunition used in the shooting, in one car, whose owner said they "might have come from her boyfriend's gun." But no record in the file shows the boyfriend was interviewed or that Thomure was asked about the bag. Thomure told the AP that the bag contained his clothing.

He also called irrelevant four instances when judges granted protection orders against him to a roommate, cousin, wife and ex-girlfriend, between 1994 and this year.

In a brief AP interview, Lyndel Robertson said he never identified Thomure as the shooter. "I said it could have been him," he said. (In fact, a state appeals court in 1997 overturned Woodworth's first conviction, saying jurors should hear that Robertson had named Thomure as a suspect.)

"I never did it," said Thomure, who now works as a mixed martial arts promoter and commodities broker in Lake of the Ozarks. "They made a judgment in that courtroom. Not once but twice. I told them everything I knew."

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A single thumb print and a common manufacturing defect found in his father's gun put Mark Woodworth in prison.

The print was found on an ammunition box inside the Robertsons' shed. Woodworth, a high school dropout who helped his father and Robertson, said the box of bullets had been moved to the shed from Robertson's pickup truck. At trial, a farm employee said Robertson regularly moved ammo boxes between his truck and the shed.

None of Mark Woodworth's fingerprints were found on his father's revolver, the purported murder weapon. An identical gun owned by Lyndel Robertson wasn't dusted for prints. No fingerprints were found on the shed or the front door of the Robertson home.

An unidentified fingerprint was found in the Robertsons' bedroom. Police and prosecutors offered no explanation for that print.

They theorized that Woodworth removed a loaded gun from his parents' bedroom while they slept and walked across the rural highway between the two homes to shoot his neighbors — but not before emptying his father's weapon and reloading it with bullets from Robertson's shed. After the shooting, he placed his father's bullets back before returning the weapon, the state suggested.

"Does it make any sense if your dad's gun is loaded to take his gun and go into the shed on the way over, open the door, get the bullets out so you can put bullets into a loaded gun and go in and shoot somebody?" Jim Wyrsch, Woodworth's first trial attorney, asked jurors.

Microscopic markings on Claude Woodworth's gun connected the weapon to a bullet removed from Lyndel Robertson's liver.

But the state's forensics expert, Steven Nicklin, acknowledged that there was "not enough detail agreement ... to conclusively link these bullets to this weapon."

Nicklin testified that he also requested Robertson's gun for testing, but it was not provided. Nor was an identical gun owned by an employee of the two farmers.

Gene Thomeczek, a retired FBI agent hired by Woodworth's family after his second conviction, found that more than 200 people in Livingston County owned the same model of Ruger gun.

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Among 10,000-plus pages of trial transcripts, investigative reports and other documents reviewed by the AP were tips from five people who reported unfamiliar cars or suspicious drivers in the area hours before the crime.

A confirmed car — especially one in the driveway, as reported by one witness, who later said he could have been mistaken — would have presented "a completely different scenario," said Gary Calvert, who as Livingston County chief deputy took charge of the investigation when the major-case squad left and who was later elected sheriff.

"We spent years trying to put a suspect with a vehicle with a weapon," he said. "And no pieces would fall together."

Private investigator Terry Deister, hired by Lyndel Robertson after the initial investigation stalled, helped persuade Calvert to focus on the soft-spoken neighbor.

The two investigators visited the Woodworth home on July 4, 1992, knowing Mark's parents weren't home. They came to discuss a vandalized combine owned by Lyndel Robertson. A four-hour interrogation then and a second session on Easter Sunday 1993 would prove pivotal to the prosecution's case.

The teenager used profanity to describe his father's former partner. Although by most accounts the 16-year partnership was thriving before the shooting, the fractured business relationship was cited as a motive. With his partner's death, Woodworth's father could cash in a $100,000 life insurance policy each man carried.

No evidence was presented in the two trials showing that Mark Woodworth knew about the insurance policy.

Another suggested motive: Robertson and his wife reportedly complained about the business having to pay Mark Woodworth $6,000 to harvest his own soybeans. Robertson, though, never mentioned such concerns until years after his wife's death. And when he faced unpaid medical bills after the shooting, Mark Woodworth gave his neighbor several thousand dollars to help out.

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A grand jury indicted Mark Woodworth in October 1993. Just five days before it was impaneled, Livingston County prosecutor Doug Roberts asked a judge to release him from the case. Now in private practice, Roberts declined comment on this decision.

But in an Oct. 5, 1993, letter to Circuit Judge Kenneth Lewis, the prosecutor noted that Lyndel Robertson asked he be disqualified for a "lack of enthusiasm." Roberts reminded the judge that soon after the crime, Robertson "was adamant that we charge another young man" — Thomure.

In a letter to the state Attorney General's Office asking for a replacement prosecutor, the judge wrote of Roberts: "He boycotted the grand jury proceedings this morning, which is simply unheard of in my experience."

"The prosecutor up there never really believed in Mark's guilt," said Phil Thompson, the retired state trooper who worked as Woodworth attorney Wyrsch's investigator. "He never felt there was enough evidence to warrant charges. That's why Kenny came up."

Kenny was Kenny Hulshof, a special prosecutor who crisscrossed Missouri assisting overmatched small-town prosecutors in high-profile cases. Hulshof went on to serve six terms in Congress and won the 2008 Republican nomination for governor before losing in the general election.

His career as a prosecutor was marked by a pattern of appeals court rulings that questioned his courtroom behavior. In February, a Cole County judge cited prosecutorial misconduct by Hulshof in the trial of Joshua Kezer, who was convicted as a teen of killing a college student. The ruling led to Kezer's release.

Asked about the Woodworth trial, Hulshof cited the verdicts by two juries "who considered the evidence and dispassionately applied the law."

But three jurors in Woodworth's second trial said it was not so clear cut.

"I just didn't think they showed us enough evidence," said juror Lisa Routh. "I'm not saying he didn't do it. There just wasn't enough evidence to say he was guilty."

Routh and two other jurors interviewed by The Associated Press said they were pressured by the other panel members to convict Woodworth — partly out of a desire to go home after the weeklong trial.

"They felt like we just wouldn't be able to get out of there if we didn't agree," said juror Dorothy Witt. "They just wanted us to all agree to the facts so they could leave."

After the verdict, Routh and Witt approached Livingston County Circuit Judge Stephen Griffin to discuss their concerns. The judge rebuffed the two women and issued a gag order preventing them from speaking with the prosecutor and the defense. Griffin did not respond to AP interview requests.

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For inmate No. 514406, life at the maximum-security Crossroads Correctional Center in Cameron is defined by routine. He works at the prison welding shop, earning $1.50 a day to help buy telephone calling cards or canteen goods.

Housed in a unit for offenders who demonstrated good behavior, Woodworth follows the hometown Kansas City Chiefs and Royals on ESPN or reads his Bible. His parents visit most weekends.

Except for two years free after his first conviction was overturned, Woodworth has spent his entire adult life behind bars.

Earlier this year, the state parole board denied his request for an early release.

"There were some holes in the case," acknowledged Robert Robinson, a recently retired parole board member. "But it wasn't enough to persuade anyone to feel contrary to what the two juries decided."

Woodworth hasn't exhausted his appeals. He says he takes comfort from the support of friends in Chillicothe, 30 miles away: "They're the ones that have given me hope."

And Woodworth, who turns 35 later this month, doesn't waver from earlier claims of innocence.

"I didn't kill them. I had no reason to," he said.