Suspects of the Zodiac killer

A number of suspects have been named. Robert Graysmith's book Zodiac advanced Arthur Leigh Allen as a suspect based on circumstantial evidence. A letter sent to the Riverside Police Department from Bates' killer was typed with a Royal typewriter with an elite type, the same brand found during a February 1991 search of Allen's residence. He owned and wore a Zodiac brand wristwatch. Allen lived in Vallejo and worked minutes away from where one of the first victims (Ferrin) lived and where one of the killings took place. In 2002, SFPD developed a partial DNA profile from the saliva on stamps and envelopes of Zodiac's letters. SFPD compared this partial DNA to the DNA of Arthur Leigh Allen. A DNA comparison was also made with the DNA of Don Cheney, who was Allen's former close friend and the first person to suggest Allen may be the Zodiac Killer. Since neither test result indicated a match, Allen and Cheney were excluded as the contributors of the DNA, though it cannot be stated definitively that it is DNA from the Zodiac on the envelopes.