* Zodiac (1986): This book is considered his magnum opus and launched his career. It's a detailed investigation of the Zodiac Killer case, based on Graysmith's own experiences as a cartoonist for the San Francisco Chronicle who became obsessed with the case.
* Zodiac Unmasked (2002): This book is a follow-up to "Zodiac," presenting Graysmith's theory on the identity of the Zodiac Killer, focusing on Arthur Leigh Allen.
* Zodiac and the Monster (2007): A short book summarizing Graysmith's investigation and his belief that Allen was the Zodiac Killer.
* The Zodiac Killer's Secret (2011): Another investigative work, this book explores the Zodiac Killer case through the lens of a recovered cipher and Graysmith's ongoing pursuit of clues.
It's important to note that Graysmith's theories about the Zodiac Killer's identity have been debated and contested by other researchers. However, his work remains highly influential in the ongoing fascination with the case.