FORT COLLINS, Colorado (CNN) -- Police are still arguing about the case two decades after the sexually mutilated body of Peggy Hettrick turned up near the trailer where a gawky teen named Tim Masters lived.

Tim Masters was 15 years old when Peggy Hettrick was brutally slain in 1987.

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When Masters was convicted and sentenced in 1999 to life in prison for Hettrick's murder, prosecutors thought they'd closed Fort Collins' then-only unsolved murder.

As court hearings resume Monday, a judge is re-examining decisions made years ago. Masters' new lawyers say key evidence was withheld during the original trial, and a special prosecutor is backing them in at least four instances.

The defense team's claims of police and prosecutorial misconduct are supported not only by the attorneys who represented Masters in 1999, but also by former police officers, investigators and forensic experts, some of whom say police ignored other viable suspects.

The case has divided a police precinct, pitted cop against cop and shattered an oft-impenetrable fraternity.

Lt. Jim Broderick, the hard-nosed Fort Collins investigator credited with cracking the case after 12 years hunting Hettrick's killer, said in a November interview that he stands staunchly by his investigation.

He declined to discuss the specific allegations at issue in the current hearings, but said he has seen no new evidence that leads him to believe Masters deserves another trial.

If a judge rules otherwise he'll accept it, he said, because "the last thing in the world I want is someone convicted of a crime they didn't do." Watch police try to bait teen Masters into murder confession »

The Fort Collins police chief said he stands by Broderick's work.

However, several authorities have told CNN they have their doubts about the fairness of the original trial and investigation. See the key players in the case »

Included are a key forensic expert for the 1999 prosecution, a former lead investigator, a former Colorado Bureau of Investigation forensic expert and two former Fort Collins police officers who say they never believed Masters did it. Also, two other former officers have testified they believe their colleagues withheld evidence favorable to Masters.

In 1999, prosecutors told a jury only Masters could have killed and maimed the 37-year-old redhead whose body was found in a field off Landings Drive on February 12, 1987.

Case history

In 1987, a bicyclist found the maimed body of Peggy Hettrick, 37, near the home of Tim Masters.

Masters, then 15, quickly became the top suspect in the slaying, but it was not until 1999 that police and prosecutors were able to convict Masters. He was sentenced to life in prison.

In hearings that began in September, Masters' new defense team is alleging police and prosecutorial misconduct in the investigation and trial. If a specially appointed judge concurs, Masters' attorneys say they plan to file a motion for a new trial.

Some think differently. They believe Masters, now 36, was convicted via faulty logic, pop psychology, underhanded investigative tactics and a collection of spooky doodles. They say Masters deserves a new trial.

"I'm not sure who killed Peggy Hettrick, but I am positive, without a doubt, that Tim Masters did not," said former Fort Collins police Det. Troy Krenning.

A single, deep stab wound killed Hettrick. After she was dead, someone -- presumably her killer -- neatly sliced away one nipple and much of her genitals.

Krenning called it a "Ted Bundy-, serial killer-type homicide" and said he doesn't believe Masters -- then a shy, bony 15-year-old -- had the strength, nerve or wherewithal to kill Hettrick, let alone carry her lifeless body 103 feet into the field. Watch doubts raised about conviction »

"I don't think Masters could have dragged a sack of potatoes into that field," said Krenning, now a regional director with the National Law Enforcement and Corrections Technology Center in Denver.

How Hettrick's body arrived in the field could be key to earning Masters a new trial, the defense contends.

Tom Bevel, a 1999 prosecution witness, told jurors he believed Hettrick was killed on Landings Drive and dragged or carried to the spot where she was found by a bicyclist the next day.

A blood-spatter expert who owns a forensic education and consulting firm, Bevel says that police failed to provide him "a litany of items" that he has now seen and that lead him to believe Hettrick was killed elsewhere and driven to the field.

Bevel wasn't aware of the items until August 2005 when he got a call from Barie Goetz, a freelance forensic expert who headed a Colorado Bureau of Investigation crime lab from 1999 to 2004.

"He was never given the physical evidence until I took it to him," Goetz said, referring to Hettrick's clothing.

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Bevel added that Goetz also provided photos and reports he had not seen. "I was never aware all those were available," Bevel said. He wrote a report for the defense last year, citing "serious concerns" with the dearth of evidence he received before his 1999 testimony.

If police gave Bevel the information they gave him in 1999, he would again testify that Hettrick was killed, mutilated and dumped in the field, he said. But after reviewing the material from Goetz, "I do not believe all of that did take place at that juncture," said Bevel.

Bevel said he has never experienced a miscommunication of this level in more than 35 years of testifying as an expert and as an Oklahoma City police officer, but he was reluctant to say police deceived him.

Goetz was less guarded: "He was certainly misled by the materials that were given to him and the synopsis."

Krenning, Goetz and Bevel are not alone in their doubts. Former Fort Collins police Det. Linda Wheeler-Holloway, a lead investigator in the early '90s and the first to point a finger at Masters, also has qualms.

When Hettrick's body was found that chilly Thursday morning, Wheeler-Holloway began interviewing potential witnesses. Among them was Clyde Masters.

"My 15-year-old son, I watched him go out the back door and head to the school bus, but then he took a little jaunt and went and stood for a minute," Wheeler-Holloway recalls Tim Masters' father telling her, pointing to a berm in the field.

Hettrick's body was lying just over the berm, but Masters had reported nothing odd to his father.

Surely, the boy reported the body once he got to school, Wheeler-Holloway thought, but he hadn't. And like that, Masters became the top suspect in the Hettrick slaying.

Broderick said a search of Masters' bedroom, school locker and backpack revealed numerous drawings and narratives suggesting the teen was fixated on death and violence.

Broderick felt the artwork and stories fit the axiom that "sexual homicide suspects generally fantasize about what they're going to do before they do it. In all likelihood, the fantasy's a template for the murder they actually commit," he said.

J. Reid Meloy, a forensic psychologist who declined to comment for this story, backed Broderick during the 1999 trial.

Police also found six survival knives with blades exceeding the requisite 5 inches it would have taken to pierce Hettrick's heart, lung and rib in one thrust. They were meticulously displayed on Masters' dresser as if part of some altar, Broderick said.

They also found a copy of Masters' mother's death certificate at the trailer and a Mother's Day card he had sent her in third grade in his backpack, Broderick said. Masters' mother, a redhead like Hettrick, had died four years earlier, almost to the day. That raised suspicions.

"It's not just unique to this guy. Look at all the terrorist and Aryan nation types. They're big on anniversaries," said Broderick.

But investigators didn't find any physical evidence -- blood, hair, skin cells. None on Hettrick. None on Masters' clothing. None at Masters' trailer.

So the prosecution built a case that went like this: Masters saw a woman with the same color hair as his mother passing his trailer, slipped out a window, fatally stabbed her just below the left shoulder blade, took her into a dark field, removed her body parts, wiped the front of her body clean and slipped back into his bedroom window.

And he did it without waking his father or the neighbors and without bringing a drop of Hettrick's blood home.

Krenning said he felt from the start, "There was no way in hell a 15-year-old could have done what was done to Peggy Hettrick and left behind no physical evidence."

It would take years for Wheeler-Holloway's skepticism to develop. She had confidence in her colleagues' conclusion that Masters was the culprit.

"The assumption was Tim Masters did it, but we just don't have enough evidence, so my marching plans were see what you can do to get Tim Masters convicted," she said.

When she took over the case, Masters was serving overseas in the Navy. Navy intelligence officers reported that Masters was a model sailor.

"How could he be so off to have committed this horrendous crime, sophisticated crime, and then be perfectly normal before and perfectly normal after?" she wondered. "But, you know, [my fellow detectives] really think he did it so I said OK."

In 1992, Wheeler-Holloway thought she broke the case when one of Masters' friends said Masters had told him Hettrick's nipple was missing.

"That's it. That's holdback information that only the cops knew," Wheeler-Holloway recalls thinking. "I thought 'OK, I got him.' "

Naval intelligence arranged for Masters to be brought stateside. Wheeler-Holloway asked Broderick to type up the arrest warrant and the pair flew with another officer to Philadelphia, Pennsylvania, with designs on bringing Masters home in handcuffs, she said.

Masters quickly pulled the arrest warrant's lynchpin. A police scout who went to school with Masters had helped search the Landings Drive field for body parts, one of them a nipple, Wheeler-Holloway said. The scout confirmed giving Masters the holdback information.

Further frustrating Wheeler-Holloway was that Masters had the same story he had five years earlier -- that he didn't report Hettrick's body because he thought it was a prank, and his stories and drawings stemmed from his ambition to write horror stories like Stephen King's.

"He didn't lawyer up. He's this real mellow, laid-back introvert -- I mean ultimate introvert -- which is not at all like a murderer's personality," she said. "I've interrogated a lot of murderers in my days. They have the ability to look someone in the eye and kill them. You can see it in their personality. So I'm talking with this kid -- he's milquetoast -- and I'm wondering how did he ever get the nerve to do this horrendous crime? He can hardly look me in the eye, you know?"

After Broderick took the interrogation baton, a naval intelligence officer asked her, "You sure you got the right guy?"

"I don't know," she replied.

Wheeler-Holloway ripped up the warrant, she said, because Masters would have cracked or deviated if he were the killer.

"It's easy to remember the truth. It's hard to remember a lie," she said of Masters' consistency.

Troubled by a seeming reluctance to pursue other suspects, Wheeler-Holloway filed the case as cold and later left the department for the Colorado Bureau of Investigation.

Broderick reopened the case a few years later, and the prosecution contacted Wheeler-Holloway to see if she would testify. Believing Broderick had damning evidence, she agreed.

"They did not have anything more than what they had had years before," she said. She warned prosecutors to "be careful because if I'm asked if I feel like he's the murderer, I'll say I'm not convinced."

The day of Masters' conviction was "one of the worst days of my law enforcement life," Wheeler-Holloway said.

"I just felt that there was indeed a real injustice, that the system failed," she said. "I was sick to my stomach."

For 20 years, Broderick has remained adamant Masters was the killer. He is quick to note that a jury, not a detective, convicted Masters.

While declining to discuss specifics, Fort Collins Police Chief Dennis Harrison said appellate courts have upheld Masters' conviction.

As for former officers expressing doubts, "they don't know the case like Lt. Broderick does," said Harrison, who has been chief since 1997.

"I don't have the doubts that have been expressed by others," Harrison said, defending Broderick. "He certainly has the support of this department."

Krenning said he testified for the defense during the current hearings because he wants to right a wrong by his former employer: "The prime of Tim's life has been taken away from him. He'll never be whole again."

Wheeler-Holloway added she wants Masters "to be truly exonerated and seen in the true light that he was an innocent person that just got wrongfully convicted. I hope to live long enough to see that day." E-mail to a friend