Detective who worked on serial killer John Wayne Gacy’s house opens up about the haunting things he saw

One of the detectives who investigated the horrific murders of John Wayne Gacy has opened up about the haunting discoveries made in the killer's home.

Rafael Tovar, who is now retired, was a member of the Des Plaines police department in Illinois when a tip came in about a missing 15-year-old boy named Robert Piest.

Police were told Piest had followed Gacy to his home in Norwood Park Township on 11 December, 1978, so went to the residence to investigate.

Gacy worked as a clown before he was arrested (Bettmann/Getty Images)

Piest wasn't found during the search, but officers noticed a strange smell which seemed to be emanating from Gacy's heating system.

That smell? Rotting flesh.

Concerned, police returned to Gacy's house with another search warrant and began searching for the source of the smell, which came from an underground crawl space.

Tovar and a team of 10 investigators began digging, which led to the first chilling discovery: a left femur bone.

Speaking to The Sun Online about the discoveries made in Gacy's home, Tovar said: "It was a bone already so we knew it couldn’t have been Robert Piest because it had only been 10 days [since his disappearance]."

Police spent months searching the crawl space (Bettman/Getty Images)

The investigators kept digging, and found another bone. But it couldn't have been from the same skeleton, because once again, that bone was a left femur.

"And then we found a third left femur," Tovar recalled. "By this point we’re thinking there’s a whole lot more here."

Police were forced to work among the 'putrid odour' coming from the bodies, but they kept going.

Surprisingly, they had help from the killer who actually drew officers a map pinpointing over two dozen bodies.

Tovar remembered Gacy telling officers he wanted them to 'be careful' that they didn't 'dirty up [his] carpets', which is why he told them 'exactly where everything' was.

"It’s a dodgy thing to say. There were 29 bodies in the house!" Tovar said.

"He had absolutely no feelings whatsoever about human life. For him, killing an individual was like stepping on an ant."

Gacy told police where to find the bodies (Bettman/Getty Images)

All in all, it took officers six months to excavate Gacy's crawl space and find the bodies of the victims he'd hidden inside.

"He had them all around the outer edges of the house and he had dug up some trenches. Some of them he put one on top of the other," Tovar said.

"It was very wet, very moist down there. You couldn’t dig with a shovel because we were afraid of breaking a bone or knocking some teeth out because that was the only way we were going to identify them, so you dug with a very small gardening tool and then you used your hands.

"We just decided to go at it. We didn’t have all the equipment we have nowadays."

Despite having retired from the police, Tovar still meets with some of the other officers he worked with on the case to this day.

"I was very proud and happy with all my colleagues who started with nothing and broke this case," he said. "But I saw the damage he did and I can’t forget."

Following his arrest, a jury found Gacy guilty of a total of 33 murders of men and boys. He was handed the death sentence, and died by lethal injection in 1994.