Zimmerman was born on June 11, 1952, somewhere in California. He first started writing while he was living in San Miguel de Allende, Guanajuato, a small colonial town located in the mountains of central Mexico. As an adult, he became involved in television, working on many TV series, among them Desperate Housewives, CSI: NY, Criminal Minds, K-Ville, The District, Judging Amy, Reunion, So Weird, and Street Time. He has also written a number of made-for-TV movies, including the two Inspectors movies for Showtime. Zimmerman has also written several novels, including four suspense novels starring the character of Quinn Parker: Blood Under the Bridge, Thicker Than Water, Full-Bodied Red, and Crimson Green.