"We were absolutely devastated, heartbroken," Walsh told Larry King on the 25th anniversary of his son's abduction. "We had nothing in common but the anger and the grief. And [Walsh's wife, Reve] said, 'You know, we're destroying ourselves. This is not something that Adam would want. We've forgotten who the real victim is.'"
The Walshes lobbied for the Missing Children Act, which was passed in 1982 and set up an FBI database of missing children. In 2006, President Bush signed the Adam Walsh Child Protection and Safety Act, which, among other things, created more stringent requirements for sex offender registration.
On July 27, 1981, Reve Walsh went with her son to the Sears department store in the Hollywood mall. She left him in the toy department playing video games. When she returned a few minutes later, he was gone. They never saw each other again.
The police, without the benefit of the missing children search tools that Walsh would later champion and modern tracking systems, were overwhelmed. "Leads are coming in and nobody's looking at them. And people are throwing them around. And I, I saw one on a napkin, I saw one here, I said, you know, there's no organization," Joe Matthews, a Miami Beach homicide detective, told ABC's Primetime in 2007.
The names of numerous possible suspects have been advanced over the years, including Jeffrey Dahmer.
Toole, a serial killer who was in prison for an unrelated murder, twice admitted to killing Adam, but recanted both times. Toole, the partner of notorious serial killer Henry Lee Lucas, reportedly confessed to committing dozens of murders, though many of those claims later proved to be false.
Police were unable to find Walsh's body in the area where Toole said it was located. During his first confession, in 1983, Toole reportedly said he used a machete to cut off Adam's head.
Police recovered a bloody piece of carpeting from Toole's car, but with no sophisticated DNA testing available at the time, police could never determine if it contained Adam Walsh's blood. The carpeting later disappeared.
Documents released Tuesday show that detectives who reexamined the case in 1996 located several people who were at the Hollywood mall on the day Walsh was abducted but who had not been shown a photo lineup during the original investigation.
Several of those witnesses said they saw Toole at the mall; one witness said he had seen Toole talking to Walsh, the documents say.
ABC News' Jason Ryan and Geoff Martz contributed to this report.