The FBI provided investigative assistance to Illinois police. In 1980, Gacy was convicted of murdering 33 young men ranging in age from 14 to 21.

n 1978, after one of Gacy’s victims, Robert Piest, was reported missing, police learned that Gacy was the last person known to have seen him. After obtaining a search warrant, police discovered the bodies of 29 boys and young men in or near Gacy’s house; four other bodies were found in the nearby Des Plaines River. Indeed, the area of the house had emitted a foul stench for years, but Gacy had told his houseguests and his wife that the smell was the result of moisture buildup. At his trial Gacy’s plea of innocent by reason of insanity was supported by the testimony of several psychologists, who diagnosed him as schizophrenic, but was rejected by the jury, which found him guilty of all 33 murders of which he was accused; he was executed by lethal injection in 1994. - Britannica

SOURCES:

https://www.newspapers.com/clip/97809682/

https://www.newspapers.com/clip/97811240/

https://apnews.com/article/chicago-2a5842ef8ee46f8d43799bc50f390ad8

https://www.britannica.com/biography/John-Wayne-Gacy

https://www.youtube.com/watch?v=J5s7WMxSplg

https://www.biography.com/news/john-wayne-gacy-timeline-murders

https://vault.fbi.gov/John%20Wayne%20Gacy

John Wayne Gacy timeline: The efforts to recover, name his 33 ...https://www.chicagotribune.com › history › ct-john-wa…

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