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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Arthur Leigh Allen was a major Zodiac suspect, but the reported forensic evidence does not tie him to the crimes: his fingerprints and palm print did not match relevant evidence, a state document examiner said his handwriting did not match the letters, and San Francisco inspectors said he did not match a partial DNA profile from genuine Zodiac correspondence. Those findings weaken the case against Allen; they do not prove who the Zodiac was. The murders remain officially unsolved, and no court cleared Allen.
Why Arthur Leigh Allen became a Zodiac suspect
Allen (1933–1992) worked as a teacher, mechanic and cashier, and was convicted of child molestation. Police questioned him in 1969 and 1971. In 1991 they revisited him after an informant facing armed-robbery charges reportedly said Allen had boasted about killing a cab driver. Allen denied being the Zodiac and died in 1992.
Allen’s prominence owes much to Robert Graysmith, whose books Zodiac (1986) and Zodiac Unmasked (2002) advanced the theory; the 2007 film Zodiac, based on Graysmith’s books, portrayed Allen as the likely killer. That narrative is not equivalent to a police finding or a conviction. The account of Allen built by Zodiackillerfacts.com is notably critical of Graysmith, so its interpretation should be read with that perspective in mind. Mainstream summaries such as Wikipedia and SFGate also report the central forensic mismatches.
What the forensic comparisons showed
Fingerprints and palm prints
An SFPD fingerprint expert compared Allen’s prints with latent prints associated with the 1969 murder of cab driver Paul Stine in San Francisco; they did not match. A palm print attributed to a writer of a suspected Zodiac letter likewise did not match Allen’s. SFPD reportedly said the same of the palm print associated with the 1974 “Exorcist” letter. These comparisons count against Allen, although they do not identify another suspect.
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Handwriting
Sherwood Morrill, California’s state documents examiner, told investigators that Allen’s handwriting did not match the Zodiac letters. That is a reported expert comparison, not a public statistical estimate of how likely a match or mismatch would be.
DNA: a mismatch, not a complete exoneration
SFPD inspectors Kelly Carroll and Michael Maloney said Allen did not match a partial DNA profile developed from genuine Zodiac letters. SFGate reported that genetic traces from letter envelopes appeared to clear Allen. But the profile was partial, not a complete identification-grade profile, and later testing did not settle the matter: detectives said in 2002 that new DNA evidence was being tested, while authorities ultimately described those tests as inconclusive. The available account supports saying Allen did not match that partial profile—not that DNA conclusively proved he was innocent.
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Witness evidence is mixed and late
A police officer who saw the Zodiac near the Stine murder scene reportedly gave a description that did not fit Allen. The strongest identification cited for Allen came much later: surviving Blue Rock Springs shooting victim Mike Mageau picked Allen from a photo lineup in 1991, saying, “That’s him,” and reportedly rated his confidence 8 out of 10. That identification came more than two decades after the July 1969 attack. Mageau’s original description did not match Allen, and accounts note that he saw the shooter only briefly, in profile. Zodiackillerfacts.com says police did not regard the identification as valid. The conflicting timing and descriptions make this a contested piece of evidence, not a decisive identification.
The accusation and circumstantial clues need context
The friend whose allegations first drew suspicion to Allen was estranged from him. According to the critical account at Zodiackillerfacts.com, the accuser changed, embellished or invented parts of his stories. That source argues against the Allen theory, so the allegation’s reliability should not be treated as settled solely on its account; no independent primary record resolving it is publicly documented.
Other often-cited details are circumstantial. Allen owned a Zodiac-brand watch, lived near several crime scenes and had a typewriter of a kind the Zodiac was thought likely to have used. None of those facts, on its own, establishes that he committed the murders. A 1991 search of his Vallejo home reportedly found writings, pipe bombs and illegal weapons, but no hard evidence connecting those items to the Zodiac crimes. SFPD inspector Dave Toschi was reported to have said investigators found no hard evidence linking Allen to the murders.
Graysmith’s claim that Zodiac letters stopped while Allen was in prison and resumed after his release has also been challenged by Zodiackillerfacts.com. Without treating that disputed chronology as established, it cannot serve as a reliable independent link.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why the case against Allen is not the same as proof of innocence
Allen’s siblings have disputed the exoneration narrative. Today.com’s account, “Who Was The Zodiac Killer? Siblings Who Knew Arthur Leigh Allen Say It’s Him,” presents their view that he was the killer. Their belief is relevant counterpoint, but it does not overturn the reported mismatches in prints, handwriting and partial DNA, or amount to forensic proof.
No reliable date-by-date alibi for Allen at the Lake Herman Road, Blue Rock Springs, Lake Berryessa or Stine attacks is established in the available accounts. There are secondary, unverified claims about his whereabouts and statements; without reliable corroboration, they should not be presented as fact. Nor is there a published probability or match statistic that quantifies the evidence against him.
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The careful conclusion is narrower than the title’s advocacy: the reported physical and forensic evidence does not support identifying Allen as the Zodiac, and no hard evidence cited here ties him to the crimes. But Allen was never legally cleared, and the Zodiac case remains unsolved. Evidence against one suspect is not identification of another.
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