Johnny

Michael Chernus

John Wayne Gacy

Gabriel Luna

Det. Rafael Tovar

James Badge Dale

Chief of Detectives Joe Kozenczak

Michael Angarano

Sam Amirante

Chris Sullivan

Lead Prosecutor Bill Kunkle

Marin Ireland

Elizabeth Piest

Greg Bryk

Harold Piest

Hamish Allan-Headley

Det. Michael Albrecht

Ted Dykstra

Det. Allen Fanholm

Cricket Brown

Kerry Piest

Alex Paxton-Beesley

Helen

Levi Shelton

John 'Johnny' Szyc

Tom Barnett

Richard Szyc

Chloe Avakian

Patti Szyc

Eva Foote

Carol Gacy

Mitchell Court

Eldest Szyc Son