As the execution hour of one minute past midnight approached, a muted crowd gathered in expectation outside the prison in Joliet, Illinois, after four last-ditch appeals by Gacy's lawyers, including one to the Supreme Court, were rejected. Earlier, hundreds of people staged a rally in Chicago, where Gacy went on his killing spree between 1972 and 1978.
As a local radio talk show host led proceedings, cheering demonstrators carried banners proclaiming 'Gacy - stick it to him', and chanted 'Goodbye Gacy' to the tune of Hello Dolly. On a nearby pavement, 33 body bags had been laid out in memory of his victims, most of whom Gacy buried beneath his suburban home. To this day, eight remain unidentified.
The macabre revels extended to a local art gallery which auctioned off paintings done by Gacy during his years on death row. 'He killed better than he painted,' was one comment. But that did not prevent a dollars 50,000 ( pounds 35,000) asking price for a portrait of Jesus Christ which had once hung in his cell. Gacy, 52, was the 237th person to be executed in the US since capital punishment was reintroduced in 1976, but only the second in Illinois in 30 years. In the event his death took more than twice as long as scheduled.
Under the lethal injection procedure, now the most common form of capital punishment in the US, a prisoner is sedated before being strapped to a stretcher trolley and wheeled into the death chamber. His arm is attached to an intravenous device, which delivers three drugs at one minute intervals: the anaesthetic sodium pentathol, then a chemical to halt breathing, and finally potassium chloride to stop the heart. However, in Gacy's case, one of the two poisons failed to flow into his body, in what a prison spokesman said appeared to be 'a problem with chemicals gelling or blood clotting in the needle'.
A curtain was pulled across the plate glass window through which two dozen witnesses were watching the execution, while a tube was replaced. Gacy, who apparently suffered no pain, was officially pronounced dead at 12.58 am.
During his six-year killing spree, Gacy would lure his victims to his house, where he sexually assaulted and strangled them. In 1980, a jury took less than two hours to find him guilty, but appeals and other legal devices kept him alive until this week.