Crime Library: Criminal Minds and Methods

The Zodiac Killer

What's Going on with the Zodiac?

By Katherine Ramsland

When the Zodiac investigation was in full swing, there had been some 2,500 suspects to process. Over the years, the police narrowed their search to a handful of men, and the prime suspects had many attributes in common: appearance, displeasure with the police, certain aspects of their lives, specific skills, and a totality of circumstances that logically fit.

The new movie singles out the most popular suspect, Arthur Leigh Allen, a child molester who died at age 58 in 1992 from failing health. He'd been fingerprinted, subjected to a grueling polygraph, searched, interrogated, and induced to give hand-writing samples. Even a year before his death, police were still investigating him, although he protested his innocence. It wasn't far-fetched that he might be the guy, given all the facts and apparent coincidence, so upon his death, investigators retrieved brain tissues for DNA testing. The technology at the time failed to prove anything.

Arthur Leigh Allen
Arthur Leigh Allen

After Allen's death, the Vallejo police named him their prime suspect in the murders in that area, according to the San Francisco Chronicle. They were hopeful when a videotape turned up among Allen's possessions postmortem, labeled with the capital letter "Z," yet it apparently contained no additional evidence against him, just a litany of insults directed at law enforcement.

Yet, that brings up a key question: with all the taunting letters and meticulous ciphers that Zodiac sent, why would he simply die and leave nothing behind to show how clever he was?  That seemed to be high on his list of egocentric priorities. One theory, based on a doctor's report, was that Allen had multiple personality disorder during the 1960s, but then recovered.

Then in 2000, as covered on A&E's Cold Case Files, San Francisco PD homicide inspectors Kelly Carroll and Michael Maloney took over the now-cold case, collecting the scattered pieces of evidence together from other jurisdictions. With more precise DNA technology available than before, they had Cynde Holt in the SFPD lab analyze the envelope seals and stamps from authenticated Zodiac letters for traces of saliva to compare against Allen's frozen brain tissue. With PCR methods, Holt replicated a partial DNA print large enough to eliminate suspects, though not to make a conclusive match. Still, it was better evidence than they'd had before.

In October 2002, the findings were announced. Allen had been eliminated as a donor of the DNA on the envelopes. At this time, they announced that they had three more letters to test, which could assist with creating a complete DNA profile, but those, too, failed to yield convincing evidence. But that result did not end Allen's association with this case.

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