
The investigation phase of the Gacy case began following the disappearance of Robert Piest and quickly escalated into one of the most intensive criminal investigations in U.S. history. This period was defined by surveillance, search warrants, and the gradual accumulation of evidence that would ultimately expose Gacy’s crimes.
Gacy’s home became the central focus of the investigation, with evidence suggesting that crimes had been committed on the premises.
Police conducted surveillance on Gacy, monitored his movements, and continued gathering evidence. As inconsistencies mounted, pressure increased. This phase laid the groundwork for his eventual arrest and confession.