For years the Zodiac was murdering victims only a few geographic miles away across several county lines with the same M.O. and nobody in law enforcement put together that the cases were linked until the Zodiac Killer himself announced that they were to several SF Bay Area newspapers.
In those days, some detective would have to read a newspaper about a slaying and think "Saaaayy... Do ya think that slaying down in Vallejo might be the same killer we got out here in Sonoma? Dah, GEE...". Either that, or the FBI thousands of miles away in Washington DC would tell them they have a problem out there in California they need to look at.
The Zodiac Killer wanted to get caught and was becoming more and more frustrated at the police for not catching him. He either died or gave up, and none of the suspects that the police kept focusing on ever panned out beyond unsupported police suspicion of "There's something I just don't like about that guy...".
There's a reason that the 1970s in California was the classical age of the serial murder hitchhiker/hooker slaying: There were a dozen or more serial killers running around leaving dead girls (and sometimes men) in the weeds all over California with impunity because they knew there was little chance they'd be caught because the police didn't have the means to effectively put two and two together: Angelo Buono/Kenneth Bianchi (the second 'Hillside Stranglers'), the Trash Bag murders, the "Original Hillside Stranger", The Freeway Killer, the I-5 Strangler, "The Original Night Stalker" (not that claim-jumping Richard Ramirez), Juan Corona, etc. The media spent more time thinking up frightening names for new serial killers faster than California LEAs kept up with new victims.
When I was a kid growing up in California, it almost seemed like the top of the news every night was another body found -- every night for several years.
Meanwhile the California Highway Patrol was spending all its time writing traffic citations against people breaking the 55 mph speed limit.
I recall a movie about Ted Bundy. The entire show was about a bunch of cops in Seattle who actually had nothing to do with his capture as far as I could tell.
Oh, I remember the Hillside Strangler(s). I grew up in L.A. in the 1970s and that case had everyone on edge, and even more so a decade later when the “claim jumper” (heh) was running around.
The Zodiac Killer is, for me at least, one of the most enigmatic cases in California history. Tied for that is the murder of Elizabeth Short (the Black Dahlia Murder).
I often wonder what happened to the Zodiac; did he just quit? Did he wind up incarcerated on a different matter and the authorities simply never put two and two together? Did he move to another state and keep up his grim harvesting of “slaves for the afterlife”?
I’d be willing to wager that he probably told people “Yep....I’m the Zodiac” and those folks probably replied, “Ah hahaha, you’re such a kidder”.
By now, if he’s still alive, he’d be an older man I figure. If he was in his 20s back in the late 60s/early 70s, he would have been born in the late 1940s to early 1950s I reckon; most likely, he was a Baby Boomer, and they’re pretty much at retirement age now, so if he’s still kicking, he’d be in his 70s or 80s. Maybe he’s in a nursing home for retired serial killers.
In any event, the Zodiac Killer will likely remain a fascinating case for armchair and amateur sleuths for decades to come.