Name	Known for
Barry Boschelli Self - Childhood Friend Self - Childhood Friend See fewer	Serious Serial Killers (2012)
James Cavanaugh Self - State Psychiatrist Self - State Psychiatrist See fewer	Serious Serial Killers (2012)
Ray Cornell Self - Fellow Inmate Self - Fellow Inmate See fewer	Conversations with a Killer: The John Wayne Gacy Tapes (2022)
David Cram Self Self See fewer	Serious Serial Killers (2012)
John Wayne Gacy Self (archive footage) Self (archive footage) See fewer	The New Detectives: Case Studies in Forensic Science (1996)
Dave Hachmeister Self - Police Investigator (as Dave Hatchmeister) Self - Police Investigator (as Dave Hatchmeister) See fewer	John Wayne Gacy: Killer Clown's Revenge (2019)
Charles Hill Self Self See fewer	Serious Serial Killers (2012)
Karen Kuzma Self - Sister Self - Sister See fewer	John Wayne Gacy: Devil in Disguise (2021)
Al Levi Self - Former Jaycee Self - Former Jaycee See fewer	Serious Serial Killers (2012)
Helen Morrison Self - Psychiatrist Self - Psychiatrist See fewer	Serious Serial Killers (2012)
Pete Stacker Narrator Narrator See fewer	Halo: Combat Evolved (2001)
Terry Sullivan Self - Gacy Biographer Self - Gacy Biographer See fewer	Serious Serial Killers (2012)
Sam Sunley Self Self See fewer	Serious Serial Killers (2012)