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The Zodiac Killer

The Zodiac Killer
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Zodiac killer case correspondence

The seemingly random brutal murders of five people in California’s Bay Area in 1968 and 1969 and a series of taunting cryptic notes sent by their killer terrorized Northern California for years.

The self-proclaimed “Zodiac Killer” sent local newspapers a three-part coded message explaining his motive for the killings in 1969 and in a separate letter to the editor suggested his identity was buried within an elaborate cipher message. The decoded message did indeed reveal the killer’s twisted motive, but his identity remains a mystery.

The unsolved nature of the murders and the Zodiac Killer’s elaborate methods of communicating with the public and his pursuers still captures the imaginations of screenwriters, authors, true-crime buffs, forensic scientists, and, of course, law enforcement.

The murders did not fall under federal jurisdiction, so the FBI never opened an investigation. But a glance through the FBI’s public records on the case shows how local law enforcement agencies called on the FBI’s expertise in handwriting analysis, cryptanalysis, and fingerprints to aid their investigations.

The FBI’s role in 1969, much as it is today, was to support local law enforcement in their investigations. In the Zodiac Killer case, correspondence between law enforcement agencies in Northern California and forensic experts at the FBI’s Laboratory—in what was then called the Technical Evaluation Unit—shows our efforts to analyze handwriting samples and lift latent fingerprints from the letters and envelopes sent by the purported killer. FBI cryptanalysts, or code-breakers, were also enlisted to unravel a complex cipher that used more than 50 shapes and symbols to represent the 26 letters of the alphabet. Ultimately the code was made public and broken by two university professors.

But then, as now, the case illustrates the extent of partnerships between the FBI and other law enforcement agencies. Here’s a look at just some of the ways we support our partners in investigations:

  • Behavioral analysis: Local police call on the FBI profilers, or behavioral analysts, at the FBI Laboratory for help and advice when leads in their criminal cases turn cold or fray into infinite possibilities. Read more about it.
  • Fingerprint analysis: Our Integrated Automated Fingerprint Identification System is the largest biometric database in the world, containing the fingerprints and corresponding criminal history information for more than 47 million subjects. Read more about it.
  • Criminal Background Checks: More than 90,000 agencies are connected to the FBI’s massive computerized database of fingerprints, mugshots, crime records, and parole and probation information. We run the “host computer” at our Criminal Justice Information Services facility in West Virginia. Read more about it.
  • Cryptanalysis: Code-breakers at the FBI Laboratory analyze and decipher codes used in used in the commission of crimes, including kidnappings, gang communications, espionage, and terrorism. Read more about it.

The records in the Zodiac case, meanwhile, are just a sample of what is available for your review in our Electronic Reading Room, which contains thousands of records, including our probes of famous persons, available through the Freedom of Information Act.

- Zodiac Killer Files
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