Richard Marshall
Richard (“Rick”) Marshall III is a possible suspect mainly because of his location during the times of the Zodiac murders. He lived in Riverside around the time of the murder of Cheri Jo Bates, and he stayed at an apartment in San Francisco that was not far from the murder scene of Paul Stine. He also worked for the KTIM radio station, where the call letters supposedly look like the same cryptic symbols that the Zodiac used in his letters.
Marshall's prints did not match the fingerprints that were collected from the Zodiac leters or crime scenes. However, this evidence can't conclusively rule him out as a suspect because we don't know everything. Marshall's handwriting had some notable similarities to that of the Zodiac.