Who was John Wayne Gacy and how many people did he kill?

CHANNEL 5 is looking into the lies behind one of the worst serial killers in American history.

John Wayne Gacy killed and sexually assaulted at least 33 boys and young men using the guise of a clown before he was eventually caught.

Who was John Wayne Gacy?

John was thought to have had quite a normal childhood after being brought up in a working-class family, however, his dad was known to be an alcoholic.

Following his childhood, he married and had a son and a daughter.

He often performed as a clown at charitable events and children's hospitals as "Pogo the clown or "Patches the clown".

He was convicted of sexually assaulting a teenage boy in 1968, four years before he went on to commit his first murder.

His wife divorced John following his conviction.

Following his release in 1970, John went on to become a fairly successful independent contractor and bought a house in Chicago.

How many people did John Wayne Gacy kill?

John is thought to have killed 33 people over six years.

He claimed his first victim in 1972, Timothy McCoy, a 16-year-old boy who he stabbed to death after picking him up from a bus terminal.

It was at his Chicago home where he would claim his victims.

He would trick boys and young men into his house and pretend to perform a magic trick on them, often in his clown persona.

After convincing his victims to put on a pair of handcuffs, he would rape and torture them before killing his captive.

He would then bury many of his victims under his house.

The most recent victim of John to be named is James "Jimmie" Byron Haakenson.

Haakenson had run away from his Minnesota home in 1976 and crossed paths with John in Chicago.

Jimmie's body was found among dozens found in a crawl space of John's Chicago-area home in 1978.

The remains were only recently identified thanks to DNA technology that wasn't available then, the Cook County Sheriff's Department announced.

At the time of John's arrest, he had claimed to investigators that the total number of murder victims could be as high as 45.

However, only 33 victims were ever linked to John. 

Investigators excavated the grounds of his property until they had exposed the substratum of clay beneath the foundations, finding 29 bodies.

How was John Wayne Gacy caught?

Police were investigating the disappearance of teenager Robert Piest with John, the last person thought to have been with the 15-year-old.

After securing a search warrant to John's home, police discovered the bodies of 29 boys and young men while four other bodies were found in the Des Plaines River.

The smell of the bodies had been building up for years but John dismissed the questions by saying it was just a build-up of dampness.

During the trial, John tried to persuade doctors that he suffered from multiple personality disorder. 

He claimed to have four distinct personalities: a hard-working, civic-minded contractor, a clown, an active politician, and a policeman named Jack Hanley, whom he called "Bad Jack." 

The defence portrayed John as a Jekyll-and-Hyde figure, presenting several psychiatric experts who had evaluated him. 

Three of these experts testified that John was a paranoid schizophrenic with multiple personalities. 

However, prosecutors contended that John was fully sane and in complete control of his actions.

Prosecuting attorney Terry Sullivan stated: "John Gacy has accounted for more human devastation than many earthly catastrophes... I tremble when thinking about just how close he came to getting away with it all."

John was found guilty of 33 charges of murder. 

He was also found guilty of sexual assault and taking indecent liberties with a child.

At the time, his conviction for 33 murders was the most for which any person in US history had been convicted.

The inhuman murderer was imprisoned for 14 years, before being put to death by lethal injection in 1994.

Now, three experts trained in exposing the lies behind serial killer's public persona examine the crimes of “The Killer Crown” in a new Channel 5 documentary.

Watch The Killer Clown: 33 Murders & Counting on Channel 5 at 10 p.m. on Sunday, October 27.