terrorized california in the late 60s, sent taunting coded letters to police, never got caught. some of his ciphers actually went unsolved for over 50 years until amateur codebreakers cracked one in 2021, didn't reveal who he was though, just more taunting.
in 2021 some amateur codebreakers actually cracked his old 340-character cipher from 1969! didn't ID him though, it was just more of his taunting nonsense.
an independent team named a guy called Gary Poste as a suspect in 2021 using DNA/fingerprint stuff, but no actual law enforcement agency has confirmed it. case is still technically unsolved.