Decades Later, New Clues in a Cold Case New revelations in the murder of "America's Most Wanted" creator's son.

Aug. 13, 2007  -- The abduction and murder of 6 ½-year-old Adam Walsh, who disappeared in 1981 from a Florida mall, is one of the most famous missing children cases in America.

It was a crime that outraged a nation and propelled Adam's father, John Walsh, to devote his life to fighting crime on the television program "America's Most Wanted."

John Walsh remains convinced the killer of his son was drifter Ottis Toole, now deceased. Walsh's longtime friend and colleague Joe Matthews has been investigating the case for a year and says he has evidence of Toole's guilt -- although the crime remains officially unsolved.

But in those chaotic early days of the investigation, in a time before amber alerts and DNA, what clues may have been missed?

Now a fascinating new theory has surfaced: Could one of the most famous murders of our time have been the work of one of the most famous murderers of all time?

For the past 11 years, a true-crime author named Arthur Jay Harris has been investigating the case on his own, and he has uncovered a shattering revelation. Who was working only minutes from that mall that morning? Jeffrey Dahmer, the serial killer.

Using public records, the 7,000-page police case file and a lot of legwork, Harris discovered that the same day Adam disappeared, two witnesses independently contacted the police to describe a thin, disheveled blond man who had been acting strangely in the mall.

Witnesses to a Crime?

Willis Morgan, a printer working for the Miami Herald, said he was accosted by this man but didn't respond, and the man suddenly stalked off. Morgan said he followed the man to the mall's toy department -- the last place Adam Walsh was ever seen.

Bill Bowen, a television producer, said he was about to enter the mall when he heard a loud altercation taking place next to a blue van. He said he saw a disheveled man holding a boy by the arm up in the air.

Bowen said the boy yelled, "I'm not going. I don't want to go," and the man screamed, "Yes you are," and then threw the boy into the van, jumped in, and sped away. Police don't dispute that these witnesses came forward at the time, although no record of their statements exists.

Ten years later, in 1991, Jeffrey Dahmer was arrested in Wisconsin for murdering 17 people. Six hundred miles apart, both witnesses saw Dahmer's photo in the newspaper and said to themselves: "That's him." Both contacted the Hollywood, Fla., police department to report that the man they had seen 10 years before in that mall was Jeffrey Dahmer.

According to former FBI agent Neil Purtell, the Wisconsin investigators had already made the Walsh/Dahmer connection the same day Dahmer was arrested. A timeline put together by police showed that Dahmer had indeed been in south Florida the day Adam Walsh was abducted. Dahmer moved to Florida in 1981, where he slept mostly on the beach and got a job working at the Sunshine Subs sandwich shop only minutes from the Hollywood Mall.

Purtell said he immediately called Florida police. "I said, 'You've got to look at this, because this guy is, is someone who was living in your area, andｻhe had already killed prior to coming into your area.'" (Dahmer killed his first victim, Stephen Hicks, in 1978, according to police.)

Purtell said more witnesses contacted the FBI to say they had seen someone matching Dahmer's description at the Hollywood Mall, although he refused to identify them. Purtell would only say that he had passed their names over to the FBI field office in Miami at the time.

Did Dahmer Do It?

Although Dahmer was living in the area at the time of Adam's murder, many in law enforcement felt that the case didn't fit Dahmer's MO. Dahmer's 17 known victims ranged in age from 14 to 36, older than Adam. However, Dahmer had been arrested for exposing himself to two 12-year-olds, and for molesting a 13-year-old.

Dahmer maintained that between 1978 and 1987 he didn't kill anyone, and some detectives believe that he had made a complete confession. However, psychiatrist George Palermo, who examined Dahmer before trial, said he had always believed there were additional victims. And Billy Capshaw, Dahmer's roommate in the Army during the year before Adam's abduction, said that Dahmer would go out at night and come back in the morning, "his shirt soaked in blood."

Perhaps the best reason to dismiss Dahmer as a suspect was that someone else had already confessed to the crime. In 1983, drifter Ottis Toole said he did it, but then recanted on videotape.

Toole: That Adam Walsh case isn't, it ain't true.

Off-Camera Voice: What isn't true?

Toole: I didn't do that case.

By 1991, Toole had confessed and recanted yet again. Though several people came forward who claimed to have seen him in the mall the day of Adam's abduction, police couldn't prove Toole had even been in the general area that day.

In 1992, Florida police interviewed Dahmer in a prison in Wisconsin. At the behest of John Walsh, who had heard that Dahmer might be involved, the Broward County district attorney took the death penalty off the table, in order to increase the odds that Dahmer would confess if he were involved.

Dahmer's denial was recorded in a transcript of the interrogation:

Dahmer: I heard it on the news but I had nothing to do with it, no.

Detective: And if you did have something to do with it, you would, you would admit to it.

Dahmer: Uh…right. Yeah.

That denial didn't ring true to agent Purtell, who asked Dahmer about it later. Purtell said Dahmer told him, "Honest to God, Neil, I didn't do it."

But then Dahmer added the words that still haunt Purtell. "He said, 'You know, Neil, anyone who killed Adam Walsh could not live in any prison, ever,'" Purtell recalled.

Purtell believes this was code for what Dahmer couldn't say directly -- if he admitted to the crime, he'd be killed in prison as a pedophile. Purtell believes this was close to an admission of guilt.

The Blue Van

But if Dahmer did murder Adam, where did he get the blue van the witness saw in the parking lot? Harris found eight witnesses who had worked at Sunshine Subs and its sister restaurant, Mr. Pizza. All reported that the restaurants shared several delivery vans which were accessible to employees. One of those vans was blue.

Capt. Smith, of the Hollywood Police Department, now questions the importance of the blue van sightings, telling ABC News he believes a family later came forward to say it was them having the altercation in the parking lot. However, Smith couldn't recall who that family was, nor could he find them in the 7,000 page file. The original lead detective, Jack Hoffman, was unable to recall the existence of this family when ABC contacted him last week.

Nine months ago, Harris published his theory in a small newspaper in Florida, but John Walsh released a statement saying the police had told him the Dahmer connection was totally unsubstantiated. When "Primetime" contacted the Hollywood Police Department and the state attorney's office three months ago, they told us Harris' theory was without merit.

If that was the case, why were they quietly interviewing Harris' witnesses? "Primetime's" cameras caught an investigator from the state attorney's office interviewing Darlene Hill, one of the co-owners of the sub shop, shortly before we did. Hill said the investigator asked her for details about the blue van.

The Meter Room

Three months ago, Harris made a key discovery: a police report lost in plain sight for 26 years. In this document, filed only 20 days before the abduction of Adam Walsh, Dahmer reported finding a dead body behind the sub shop, just outside a deserted meter room. A cursory autopsy revealed that the man -- a derelict who had been sleeping in that meter room -- died of natural causes. Smith of the Hollywood Police Department had never seen this report until we showed it to him.

Harris believes that report offers a potential answer to an important question: where Dahmer could have taken Walsh.

"I'm tracking the path to Jeffrey Dahmer. And, figurative doors are opening. And then a literal door opens: the door to that meter room," Harris said. "Primetime" hired Jan Johnson, a Florida licensed crime scene investigator, and with the owner's permission, we went into that meter room. It seemed mostly untouched by time.

Using an alternate light source, Johnson found what she said looked like a pattern of blood spatter in a corner of the room -- more than 100 dried droplets rising up in a pattern from near the floor. She also found an axe and a sledgehammer.

Several samples collected from the spatter on the wall tested positive for blood. However, sophisticated lab tests done later determined the samples were simply too corroded by time to be able to distinguish if the blood was human—or to get traceable DNA.

Johnson, who is also an expert on blood spatter, felt the room merits additional testing. "In my opinion the scene needs to be further examined to put closure to it."

America's Most Wanted

John Walsh, who declined our request for an interview, remains convinced that the killer of his son was Ottis Toole. Walsh's longtime friend and colleague, Joe Matthews, said that he (Matthews) now has proof that it was Toole, but declined to show it to us. He said he is waiting to reveal his evidence on an episode of "America's Most Wanted" this fall.

The one thing that's certain is that everyone involved, no matter what theory they believe, wants to see this case solved. "It was a crime not only against a child and a family, but it was against a community as well," said Harris.

"I think anytime doubt's raised, you have to, you just owe it to the investigation to resolve it," said Purtell. "Because that's…that's what you do. That's what the word 'investigator' means."