Season Regulars 3

1. 

   John Wayne Gacy

   Self (archive footage)

2. 

   Robert K. Ressler

   Self - Ret. FBI Profiler (archive footage)

3. Terry Sullivan

   Self - Fmr. Prosecutor, Cook County, IL

Guest Stars 13

1. 

   Jay Levine

   Self - Ret. News Anchor & Chief Correspondent

2. David Hachmeister

   Self - Ret. Des Plaines Police Officer

3. 

   Anthony Antonucci

   Self - Former Gacy Employee

4. Rafael Tovar

   Self - Ret. Des Plaines Police Detective

5. Lawrence Finder

   Self - Fmr. Prosecutor, Cook County, IL

6. Michael Albrecht

   Self - Ret. Des Plaines Police Officer

7. 

   Karen Kuzma

   Self - John Gacy's Sister

8. William Kunkle

   Self - Fmr. Chief Prosecutor, Cook County, IL

9. Ray Cornell

   Self - John Gacy's Former Friend

10. Patti Szyc-Rich

    Self - John Szyc's Sister

11. Eugenia Godzik

    Self - Gregory Godzik's Sister

12. Ron Wilder

    Self - Jeffrey Rignall's Partner

13. Sam Amirante

    Self - Gacy's Attorney (archive footage)

Crew 29