Gacy murdered for the first time in January 1972. He eventually opened his own construction business. The purpose of this was to lure young boys into his home. He would offer them a job and when they came for an interview he would often rape and kill them.
One of his victims, Rick Johnston, disappeared after going to a rock concert on August 6, 1976. He met Gacy, who offered him a lift. He was then taken back to Gacy's house where he was raped and strangled.
On May 22, 1978, Jeffrey Ringall decided to walk through his home town of Chicago after returning from a winter vacation in Florida. While walking the streets, he was complimented by a heavy-set man driving an Oldsmobile. This man was Gacy. He continued to make small talk, and asked Ringall if he wanted to smoke with him. Ringall agreed, he hopped in the car and began to smoke with Gacy, who quickly shoved a rag, doused in chloroform, over the young man's face. Ringall lost conscoiusness, and woke up in Gacy's house, with Gacy standing naked before him. Ringall was viciously raped, tortured, and drugged that evening. He suffered severe emotional trauma, yet he was lucky to be alive. He was one of the few victims to have survived. Another victim, Robert Donnelly, also a survivor, had a very similar story even though these crimes both happened on different days.
Robert Piest, a stock boy at a local pharmacy, had come up missing on December 12, 1978. Gacy was the last person seen with the teenage boy. While searching Gacy's home, investigators found a receipt for a roll of film, that belonged to a co-worker of Robert Piest, which was given to Robert on the day of his disappearance. In April 1979 the remains of Robert were discovered along the Illinois River. Autopsy results determined that he died as a result of suffocation.