The Zodiac Killer was an unidentified serial killer who is believe to have operated during the late 1960s and early 1970s and is particularly famous for his or her habit of communicating with police and newspapers; the Zodiac Killer is known to have placed multiple calls to police departments, in addition to sending a series of coded messages to local newspapers. There are a total of five confirmed murders attributed to the Zodiac Killer, though the killer claimed in his or her communications with the media to have killed up to 37 individuals. The crimes that are attributed to the Zodiac Killer all took place in northern California, mostly around the San Francisco Bay Area, with the alleged murderer habitually contacting police departments and newspapers in that area.
There are multiple reports of a person calling local police departments near murder scenes believed to be the work of the Zodiac Killer. In these phone conversations, the caller reports intimate details of crimes, indicating knowledge that could belong to the individual who committed the crimes. The Zodiac Killer is perhaps more famous for the cryptic letters he or she sent to area newspapers such as The San Francisco Chronicle. In some cases, these cypher puzzles were submitted to the public so they could be solved, adding public interest to the case.