Not true to the events of his life...*spoilers*
I just watched this film and decided to read about Gacy on the internet a bit as i felt the film was quite weak and wondered how much they changed to fit the short running time.
Gacy had a son and a daughter not two girls. His wife also divorced him after he was imprisoned for raping a young boy/man of about 18. The marriage portrayed in the film was in fact his second wife, a big chunk of his life was simply missed out. He never owned KFC or similar branches of a franchise, he worked for them by appointment of his father in-law before his divorce.
These are just a few of the things ive read up till now and ive only read a couple of chapters of the online crime library.
Why was so much changed? I cant think of a reason for it, it simply affected the integrity of the entire film, not that i was expecting a masterpiece but it was simply very poor of the people involved in making this film.
ultimately I do not particularly recommend viewing this to anyone unless perhaps you are extremely bored and it happens to come on tv. Watch Ted Bundy instead, that was far better researched and the end product is simply a more interesting and scarier viewing experience.