Zodiac Killer letters to the San Francisco Chronicle

In 1969 the person who identified themself as the Zodiac sent taunting letters and ciphers to the San Francisco Chronicle and other Bay Area newspapers; these communications are central to the Zodiac murders investigation. Several of the letters were received at the newspaper's offices, and the sender's identity remains officially unknown despite decades of investigation and competing theories. Portions of the case, including authorship and motive, continue to be debated by law enforcement and researchers.