If you like cold case documentaries with only a mere frisson of cryptography, “Cold Case Files 1: The Zodiac” (which was recently uploaded to the TagTele site) could well be for you. While it’s an oldie (first released way back in 2003), it doesn’t try to impose any theories, but concentrates on interviewing people who were actually there… well, up to timecode 25:40, anyway, when it suddenly goes into ‘Arthur Leigh Allen = prime suspect’ mode (but then constantly bangs on about how he almost certainly wasn’t the Zodiac). Which is nice.
video since removed from TagTele site
What I wasn’t expecting was that – quite the opposite from what you might think from 2017’s documentary crop on the History Channel (which is an anagram, not many people know, of Clannish Theory, Shithole Cranny, and Horny Chatlines) – the police had actually worked through lots of the Zodiac DNA evidence by 2002. In the video, the specifically DNA-based angle (which starts at about timecode 33:25) shows that when DNA from Arthur Leigh Allen’s preserved brain was compared with the best reference samples derived from Zodiac primary evidence, it was enough to exclude him from being the Zodiac Killer.
Moreover, the documentary also discussed “writer’s palm” (from about 36:50 onwards), which is the imprint left by someone’s palm as they write a document. What it revealed (which I didn’t know) was that the palm prints police forensically recovered from Zodiac letters were good enough to compare with palm prints taken from Arthur Leigh Allen: all of which also proved that he was not the Zodiac Killer.
Of course, while it sounds ever so intriguing that Arthur Leigh Allen had a Zodiac watch, he was actually a scuba diver, and that was basically who Zodiac watches got marketed at. As an aside, I do wonder if the police ever looked at SF scuba clubs of the period: that may have been more of a productive avenue to explore than the American Cryptogram Association. Ah well. :-/
Incidentally, if you want to see a young-looking Tom Voigt, he’s in the documentary from about timecode 40:15, with the voiceover saying that his website gets a million hits per month (back in 2003). Goodness knows how much traffic it must get now, blimey. :-/