John Wayne Gacy, convicted in 1980 of the sexual assault and murders of at least 33 young men and boys in the 1970s, was executed by lethal injection at Stateville Correctional Center in Illinois on October 10, 1994. Gacy’s crimes — many victims were buried beneath his Chicago-area home and others disposed of in nearby rivers — made his case one of the most notorious in U.S. criminal history and prompted extensive media coverage and public attention to serial murder investigations and offender profiling. Gacy was arrested in December 1978 after police investigating the disappearance of one young man discovered human remains at his Norwood Park home and on nearby property. In March 1980, following a high-profile trial in Cook County, a jury convicted Gacy of multiple counts of murder. He was sentenced to death and spent the next 14 years on death row while exhausting appeals and post-conviction remedies. His case involved numerous petitions to state and federal courts, discussions of mental competency, and debates over legal procedure and evidence — all part of the protracted process typical of capital cases in the United States. On October 10, 1994, after state courts and the U.S. Supreme Court declined further stays, Gacy was executed by lethal injection. Corrections officials reported that the execution proceeded according to protocol for the state at that time. The execution closed a chapter that had lasted more than a decade in the courts and nearly two decades since the crimes themselves. Gacy’s convictions and execution had broader impacts. The scale and nature of his crimes contributed to changes in investigative techniques, interagency cooperation, and public awareness of missing-person cases. Victim recovery and identification continued for years after his arrest; forensic work, including advances in forensic anthropology and later DNA testing, aided identification of several victims. The case also prompted ongoing discussion about capital punishment, victims’ rights, and how the criminal justice system handles appeals and post-conviction review. Historical accounts of Gacy’s crimes and trial are based on court records, police reports, contemporary news coverage, and subsequent investigative and scholarly work. Some details remain the subject of continuing research and, in a few instances, debate among historians and forensic investigators. The basic facts of his conviction, sentence, and execution are documented in public records from Cook County courts and the Illinois Department of Corrections.