Arthur Leigh Allen was a former elementary school teacher and convicted sex offender, and the only person ever publicly named as a suspect by police in the Zodiac Killer case. He died in 1992. Allen denied being the Zodiac. He was interviewed from the early days of the investigation and was the subject of several search warrants over roughly two decades.
According to Robert Graysmith (2007), several detectives described Allen as the most likely suspect; Graysmith referred to him under the pseudonym “Robert Hall Starr” in his 1986 book Zodiac (book) before writing about him directly in Zodiac Unmasked (2002). In contrast, Dave Toschi stated in 2010 that the evidence against Allen ultimately “turned out to be negative.”
Conflicting accounts
In a 2002 partial DNA profile developed from saliva on stamps and envelopes (especially the November 8, 1969 card), Allen’s DNA was not a match. Researcher Tom Voigt argued the DNA may have come from the front of a stamp and could belong to someone else, leaving the result inconclusive rather than exculpatory.