 Certain episodes have also featured commentary from famed demonologist and clairvoyant Ed and Lorraine Warren, who have actually investigated some of the cases featured on the series.The episode "The Dark Side" was dedicated to the memory of Ed, who died in 2006.The show originally aired from August 6, 2002 to November 9, 2007 on the Discovery Channel, which produced four seasons of 39 episodes.