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The Zodiac Killer was an unidentified serial murderer who operated in Northern California and sent taunting letters and ciphers to newspapers and police. The FBI assisted local agencies chiefly through Laboratory examination, document comparison, and coordination of communications connected to the threats. The released records visible here include 1969 airtels, Laboratory transmittals, FOIA deletion sheets, and descriptions of letters, envelopes, and cipher sheets sent to the San Francisco Examiner, San Francisco Chronicle, and Vallejo Times-Herald. The OCR shows the Bureau cataloged questioned documents such as the "This is the Zodiac speaking" Examiner letter received by Vallejo police in August 1969, a Vallejo Times-Herald letter postmarked July 31, 1969, and related cryptograms. Laboratory notes refer to examinations of hand printing, paper, watermarks, and possible source information, while some pages were withheld under FOIA exemptions.

FBI file number: 9-HQ-49911 | Documents span: 1969 | Released in 7 parts
Names in this file: Zodiac Killer
Subjects: serial murder, ciphers, threat letters, handwriting analysis, FBI Laboratory, California