Michael Butterfield is a leading expert and writer on the Zodiac case who has studied it since the 1990s. He has acted as a consultant for several television documentaries including the History Channels The Hunt for the Zodiac Killer and Reelzs The Real Story of Zodiac, and was also a consultant for the major motion picture Zodiac (2007). He is also the producer of the podcast series Zodiac: A to Z and is a contributing author for True Crime: Case Files, True Crime Magazine, and the two volume collection of essays titled A History of Evil in Pop Culture. He also co-authored the book Zodiac Killer Interviews.