The former defense attorney for "killer clown" John Wayne Gacy said the serial murderer may have dozens more victims in addition to the 33 young men he killed in the 1970s.

Gacy – dubbed the "killer clown" for his performances as a clown at children's parties – was convicted in the slayings of 33 boys between the ages of 14 and 21. Authorities said he would rape and torture his victims prior to murdering them. 

Most of their bodies were discovered buried in the crawl space below Gacy's Norwood Park Township home in Illinois, while a few remains were concealed around the property. Four bodies were dumped in a nearby river in the Chicago suburb.

Karen Conti, Gacy's only female defense attorney, said the number of victims is likely off.

"How many more bodies could there be? I could guess another 20," Conti told the U.S. Sun.

She said Gacy also may not have acted alone.

"While there are hints and suspicions, definitive evidence is elusive. Gacy's records show he was out of town during certain disappearances, and there could be more co-conspirators involved," including political figures, said Conti.

"There are conspiracy theories that Gacy was protected by people in power. I've heard that many, many times," she said, explaining Gacy was well-liked in the community.

"I'm not sure I have the facts to prove that, but he was connected. And there were rumors that Gacy had a list of people who may have been gay and involved in some of this. People lived double lives," said Conti.

Brian Peck, Nickelodeon star Drake Bell's former dialogue coach, also had ties to the serial killer. In Quiet on Set: The Dark Side of Kids TV, former All That actor Kyle Sullivan said Peck and Gacy wrote letters back and forth.

"Brian actually developed a pen pal relationship with John," Sullivan said of Peck, who was convicted of sex crimes involving a minor. "He kept this pile of letters and photos from John Wayne Gacy in his nightstand next to his bed." 

Peck allegedly displayed a signed clown painting gifted to him by Gacy at his California home.

"Brian flipped the thing around and on the back it said, 'To Brian, I hope you enjoy the painting. Best wishes, your friend, John Wayne Gacy,'" accused Sullivan.

Gacy was executed by lethal injection on May 10, 1994. He was 52 years old.