John and Reve Walsh were planning to have a second child, a brother or sister for their 6-year-old son Adam, back in the summer of 1981.

But on July 27 of that year, their lives turned upside down. Adam was in the video game department of Sears, near their home in Hollywood, Fla., while his mother was looking at lamps just three aisles away.

When some older boys got into a fight over the games, Adam was ushered outside with them and left alone in the parking lot, according to America's Most Wanted, the long-running television show that was launched by John Walsh.

That was when Adam vanished. And that was the day the Walshes launched what America's Most Wanted calls "the largest manhunt for a missing child in the state of Florida."

Two weeks later, the Walshes' hopes were shattered when their little boy's head was found 100 miles away, in an irrigation ditch in Vero Beach, Fla.

In 1983, serial killer Ottis Elwood Toole confessed to killing Adam with Henry Lee Lucas, another serial killer whom Toole called his "crime partner and homosexual lover."

But then Toole recanted the story and confessed to the killing himself, according to America's Most Wanted.

Toole said he lured Adam into his Cadillac with candy, then choked him and chopped his head off with a machete because he feared the boy might be able to identify him.

Three months later, he recanted again.

Toole died in a Florida prison in 1996, but the investigation remained open for another 12 years.

On Thursday, 27 years after Adam was murdered, police in Hollywood, Fla., said that Toole had confessed to the boy's murder on his deathbed, and they declared the case was closed.

Click here to read more on the murder of Adam Walsh from America's Most Wanted.