The Zodiac Killer Ciphers

Between 1968 and 1969, a serial killer terrorized the San Francisco Bay Area, murdering at least five people and claiming responsibility for many more. The killer, who called himself the Zodiac, sent taunting letters to newspapers, some containing cryptic ciphers. The killer was never identified, and his final cipher remained unsolved until 2020.

The Crimes

The confirmed Zodiac victims were killed in seemingly random attacks between December 1968 and October 1969. The killer targeted young couples in isolated locations. He shot or stabbed his victims, often with no apparent motive.

The Zodiac claimed responsibility for as many as thirty-seven murders, though only five have been confirmed. He may have stopped killing or simply stopped communicating.

The Communications

Beginning in 1969, the Zodiac sent letters to Bay Area newspapers. The letters included pieces of evidence, threats, and cryptograms. He demanded publication of his ciphers or threatened to kill more victims.

The Ciphers

The Zodiac sent four ciphers to authorities and newspapers:

The first cipher, a 408-character cryptogram, was solved within a week by a schoolteacher and her husband. It revealed a disturbing message about killing for thrills but did not identify the killer.

The second cipher, 340 characters, remained unsolved for over fifty years. In December 2020, a team of codebreakers finally cracked it, revealing another taunting message.

The remaining ciphers, shorter sequences of characters, remain unsolved.

The Investigation

Despite the most intensive manhunt in San Francisco history, the Zodiac was never identified. Numerous suspects have been proposed over the years, but none has been definitively linked to the crimes.

Assessment

The Zodiac case represents one of America’s most infamous unsolved serial killer investigations. The cryptic communications, the unsolved ciphers, and the killer’s apparent ability to evade capture have made it an enduring mystery.