Updated

The investigation into the 1981 murder of Adam Walsh, the 6-year-old son of "America's Most Wanted" anchor John Walsh, is finally closed.

Hollywood, Fla., Police Chief Chad Wagner announced Tuesday that the department had concluded that Ottis Toole, a serial killer who died in jail in 1996, was the man who kidnapped and decapitated the young boy.

Click here to see photos related to the case.

The announcement brought to a close a case that had angered the Walsh family for more than two decades, inspired the television show about the nation's most notorious criminals and triggered changes in how authorities search for missing children.

"Who could take a 6-year-old and murder and decapitate him? Who?" an emotional John Walsh said at Tuesday's news conference. "We needed to know. We needed to know. And today we know."

The Twisted Life of Serial Killer Ottis Elwood Toole

Adam disappeared from a Hollywood mall on July 27, 1981. Two weeks later, fishermen discovered his severed head in a canal 120 miles away. The rest of his body was never found.

Toole confessed twice to the boy's murder, but he had confessed to hundreds of other killings, and police determined most of those confessions were lies.

Officials were never able to verify his confessions because of a series of errors they made in the investigation, including losing the bloodstained carpeting from Toole's car — preventing DNA testing — and losing the car itself.

Toole's niece later told Walsh that her uncle gave a deathbed confession to Adam's murder in September 1996.

Wagner acknowledged and apologized for the mistakes that were made in the investigation, but he said detectives were always led back to Toole.

"Our agency has devoted an inordinate amount of time seeking leads to other potential perpetrators rather than emphasizing Ottis Toole as our primary suspect," he said. "Ottis Toole has continued to be our only real suspect."

For all that went wrong in the probe, the case contributed to massive advances in police searches for missing children.

Adam's death, and his father's subsequent activism, helped put faces on milk cartons, started fingerprinting programs, increased security at schools and stores and spurred the creation of missing persons units at every large police department.

It also prompted legislation to create a national center, database and toll-free line devoted to missing children, and led to the start of "America's Most Wanted," which brought those cases into millions of homes.

With the case now closed, Wagner said he hoped the Walsh family could find some closure.

"The not knowing has been a torture, but that journey's over." John Walsh said.

The Associated Press contributed to this report.