A serial killer who murdered at least five people in Northern California in the late 1960s and early 1970s, taunting police and newspapers with cryptic ciphers.

The Zodiac Killer murdered at least five confirmed victims and seriously wounded two others in Northern California between 1968 and 1969. The killer sent encrypted messages and taunting letters to local newspapers, challenging authorities to decipher his identity. He claimed responsibility for as many as 37 murders, though only five have been confirmed.
On December 20, 1968, a high school couple was shot and killed in their car on Lake Herman Road near Benicia, California. This is considered the Zodiac's first confirmed attack.
The killer sent four cryptograms to newspapers. The first cipher, "Z408," was solved within a week by a teacher couple. The "Z340" cipher remained unsolved for 51 years until an amateur codebreaking team cracked it in 2020. The "Z13" and "Z32" ciphers remain unsolved.