The Zodiac Killer is the Bay Area's biggest unsolved mystery, no contest. He's right up there with Jack the Ripper in unsolved mystery lore. But you've heard the story a million times. How about some mysteries you haven't heard before?

Did you know that in 1957, a luxury airliner left SFO for Hawaii and was never seen again? Or how about the mass grave in Santa Cruz? There's even a serial killer who killed up to 14 men he met at gay bars in the 1970s — and we know almost nothing about him.

"The Doodler" had a particularly sinister signature. Before stabbing his victim to death, he would draw a sketch of them — hence the nickname. The bodies were found in Ocean Beach, Lincoln Park and Spreckels Lake; police believe the Doodler met his victims for sexual encounters in those locations, sketched them and then murdered them.

Don't miss this newsreel footage of one of San Francisco's enduring mysteries: The missing blimp crew: 

Newsreel footage shows a neighborhood crowd around a crashed US Navy Blimp in Daly City in 1942.

Media: San Francisco Chronicle

Three victims of the Doodler survived but, in a sad sign of the times, refused to testify because they feared outing themselves by doing so. The Doodler stopped killing in 1975 and no one was ever charged in the killings.

MORE: The 16 most infamous crimes in Bay Area history

What are some obscure California mysteries that you want answers to? Leave your biggest questions in the comments below, or check out the California Department of Justice's cold case investigations database.