“America’s Most Wanted” is a television show that ran for 25 seasons and resulted in the captures of over 1,000 criminals. Though the show was incredibly popular during it’s run, few fans knew the heartbreaking story behind John Walsh agreeing to host it.

Back in 1981, Walsh’s wife Revé was shopping with their 6 year-old son Adam at a department store in Hollywood, Florida when she left him for just a second to look in a different aisle. When she returned, Adam was gone, and she could not find him anywhere.

Police searched tirelessly for Adam, but they could not find a trace of him. It was not until two weeks later that Adam’s severed head was found in a canal.

Though there were no leads on Adam’s killer, Walsh and his wife were determined to make sure that no other family would have to go through this. Just days after burying their son, the couple began campaigning to change the way police investigate cases of missing children.

Walsh and Revé’s efforts led to the passing of the Missing Children’s Act and the founding of the National Center for Missing and Exploited Children, the group that famously started putting photos of missing children on milk cartons.

Walsh became so associated with campaigning to help find missing children that he was chosen to host “America’s Most Wanted,” and he did so for 25 years. Though he enjoyed hosting the show, he admitted that talking to the parents of missing and murdered children was tough for him.

“I’ll always be the parent of a murdered child,” he said in 2009. “Adam will always be in my mind. Your heart is broken. It doesn’t matter if it was six months ago or 27 years ago. Your heart is broken. People deal with it differently. Some descend into hell in different ways and you live in that hell.”

It took years, but police finally determined that Adam’s killer was serial killer Otis Toole, who confessed just before his death in 1996. The Hollywood police department said that he was almost certainly the killer and apologized to the Walsh family “investigative mistakes that transpired during the early years of this investigation.”

Walsh was just glad that his family finally knew who had killed their son.

“Who could take a six-year-old and murder and decapitate him? Who?” Walsh said in 2008. “We needed to know. We needed to know. And today we know. The not knowing has been a torture, but that journey’s over.”

Walsh continues to help victims on his CNN television show “The Hunt,” and he hopes Adam would be proud of all he’s accomplished.

“I think wherever he is, he is [proud,]” Walsh said. “I don’t know, I hope so. I loved that little boy.”