Zodiac Killer letters received by the San Francisco Chronicle

Between 1969 and 1974, an unidentified person known as the Zodiac sent multiple cryptic, taunting letters and ciphers to the San Francisco Chronicle that claimed responsibility for several murders. Portions of the ciphers remain disputed or unsolved, and the Zodiac's identity has not been conclusively established. The Chronicle's offices were a primary recipient of those communications and served as a key public forum in San Francisco for reporting and analysis of the case.