July 27, 1981, quickly went from a normal day for the Walsh family to one that seeped into tragedy.

Reve Walsh and her 6-year-old son, Adam, went to Sears in Hollywood, Florida, on that day. While at the store, the boy went into the video game aisle while his mother browsed just a few aisles over, History.com reported.

When his mother went to the aisle to retrieve her son, he was gone. Investigators discovered that Adam left the store with a group of older boys who were asked to leave for causing trouble, according to the source.

THE KIDNAPPING OF KAMIYAH MOBLEY: THE 8-HOUR-OLD BABY ABDUCTED FROM FLORIDA HOSPITAL ON THIS DAY IN 1998

Adam’s parents launched a massive hunt to find him, and they even put up a $100,000 reward to draw attention to the case.

“When Adam was kidnapped … the FBI did not help us,” Walsh previously told Fox News Digital. “… The FBI refused to enter Adam in the NCIC, or the National Crime Information Computer, which, at the time in 1981, stored millions of records of convicted felons, stolen boats, stolen cars, stolen planes. … There was no unidentified dead file, no missing children’s file, nothing.”

Less than two weeks after Adam went missing from the department store, his severed head was found by two fishermen in a drainage canal in Vero Beach, about 100 miles from where he was abducted, according to History.com. His body was never found.

SERIAL KILLER SURVIVOR WONDERS WHY HE WAS SPARED AFTER CHILLING CAR RIDE: ‘HE WAS A MONSTER’

“I was dying of a broken heart,” Walsh told Fox News Digital when the tragic discovery was made.

It would take 27 years for Adam’s case to finally close.

Ottis Elwood Toole would eventually confess to Adam’s murder, but his story was given and recanted many times over the years after the discovery of Adam’s murder. 

In October 1983, Toole, who was an inmate at a Florida prison, originally confessed to Adam’s abduction and murder, according to History.com. He alleged that serial killer Henry Lee Lucas was also involved in the crime, though it was later discovered that Lucas was in jail at the time of the kidnapping.

TRUE-CRIME PODCASTER ATTEMPTS TO SOLVE FATHER’S ‘STRANGE’ MURDER: ‘HE DID NOT DESERVE TO DIE IN THIS WAY’

Investigators were unable to locate Adam’s body in the location Toole claimed to have buried it, providing no physical evidence to the case. 

Several months after his confession, Toole recanted.

In the following years, Toole continued a cycle of confessing and taking back his story. Another possible suspect of Adam’s murder was serial killer Jeffrey Dahmer, who was living in Florida at the time, according to History.com.

Toole, who was convicted of six murders, died behind bars in 1996. It wasn’t until Dec. 16, 2008, when the police department announced that the case was closed with enough evidence to declare Toole responsible for Adam’s death, according to History.com.

CLICK HERE TO GET THE FOX NEWS APP 

Since then, Adam’s family, including younger brother Callahan, who was not yet born at the time of Adam’s disappearance, have dedicated themselves to a life of advocacy.

John is the creator and host of the show “America’s Most Wanted,” which has been hunting down criminals for more than 40 years. He launched the series in 1988 after his son’s murder. 

“I grew up in a nice, gated community [and] didn’t think crime would touch us,” Walsh previously told Fox News Digital. “… I’ve learned in all of these years that the bad guys will come right into your area. It doesn’t matter who you are or where you are. They can do something to you and get you.”

The show has helped capture more than 1,190 criminals.

“What drove me was that no one helped us look for Adam,” Walsh previously told Fox News Digital. “We put a man on the moon, and we couldn’t put missing children into the big FBI computer. But we persevered. We loved that little boy so much, and we didn’t have a clue who murdered him. It took 27 years to find out. It was a wonderful retired detective and DA who looked at those files, discovered Adam’s murder and solved Adam’s case. But it’s that driving force, our love for him, that has pushed me.”

CLICK HERE TO GET THE FOX NEWS APP 

Walsh is also a co-founder of the National Center for Missing & Exploited Children, a nonprofit organization for which Callahan serves as the executive director of its Florida branch.

On July 27, 2006, 25 years after Adam’s disappearance, President George W. Bush signed the Adam Walsh Child Protection Safety Act into law, “which created a national database of convicted child sex offenders, strengthened federal penalties for crimes against children and provided funding and training for law enforcement to fight crimes involving the sexual exploitation of children via the internet,” per History.com.