Ottis Elwood Toole, the man who police identified on Tuesday as the killer of 6-year-old Adam Walsh in 1981, was the lover and partner in crime of serial killer Henry Lee Lucas.

He admitted to having committed his first murder at 14, running over a traveling salesman who propositioned him for sex with the salesman's own car, according to Biography.com. It's not known exactly how many people Toole killed, but after his mother's death in 1981, he claims to have killed nine people in six states.

Toole met Lucas in 1978, and the two "joined forces as a homosexual crime team, criss-crossing the country from 1978-1983," according to America's Most Wanted, started by Adam Walsh's father John Walsh.

In 1982, Toole killed a 64-year-old man in Jacksonville, Fla., and in April 1984 he was sentenced to death for the murder. That same year, he was sentenced to death for murdering a 19-year old woman from Tallahassee in 1983, but both sentences were reduced to life in prison, according to America's Most Wanted.

In October 1983, he confessed to kidnapping and murdering six-year-old Adam Walsh, but he later recanted.

Toole pleaded guilty to four more murders and received four more life sentences in 1991, America's Most Wanted reports.

In prison, Toole briefly lived in the cell next to notorious serial killer Ted Bundy in Raiford Prison in Florida, Ann Rule wrote in her 2000 biography of Bundy, "The Stranger Beside Me."

Toole died in prison on Sept. 15, 1996, from liver failure.

Click here to read more on Ottis Toole from America's Most Wanted.