The miniseries follows Nilsen and his biographer, Brian Masters, who grew obsessed with the murderer overtime.
The actor remembered that he was given a smaller chair than other cast members on set of "Harry Potter and the Goblet of Fire."
Author Neil Gaiman accompanied David Tennant, Michael Sheen, Miranda Richardson and Jon Hamm to discuss Amazon's long-awaited adaptation of "Good Omens."
"You suddenly realize the potential for destroying peoples' fantasy of these characters."
As Richard II, the former Doctor Who brings his own manic Shakespearean spin to Brooklyn.
The hit show starring David Tennant and Olivia Colman will conclude as the show's creator takes over 'Doctor Who'.