It is evidently clear from the discussion that John Wayne Gacy was a serial killer who is known for killing 33 boys and young men and burying them under the crawlspace in his home. Gacy was a charming, and interesting man, and he had status in his community as a businessman who also worked for the charity. Gacy also did children’s parties as Pogo, the clown. Gacy claimed that it was not he who committed these crimes, but someone named Jack which alluded to a split personality. Psychiatrists found no evidence of a split personality. Gacy confessed his crimes in 1978 after police found the boys bodies in the crawlspace. He spent 14 years in prison and was executed in 1994. The case of John Wayne Gacy follows many of the same patterns as other serial killers because he abducted a certain type of boy and brought them to his home. He would engage the boys in some type of playing and often wrestling, have sexual intercourse with them, and then kill them. Once he understood what he had done, he would bury them in the crawlspace and then go on living his normal life until he found another boy. Because he owned a construction company that employed teenagers and young men, he was able to have a steady flow of boys as he wanted. Gacy has been called the most vicious of the serial killers because he killed so many people before he was caught. This paper will present information about the crime scene, the victimology, investigation, forensic findings, the motive for his crimes and information about the trial. He was convicted of more murders than any other killer in American history. The crime scene has been described as gruesome and smelling like death. The crime scene did not become apparent to the police until the family of one of the boys, Robert Piest, was missing. Once he was missing, and it was known that Gacy was the last person to see Piest, the police began to watch him closely.