Tonight we are going to be looking into the case of The Zodiac Killer, an American serial killer who operated in Northern California from at least the late 1960s to the early 1970s. The unidentified killer originated the name in a series of taunting letters and cards sent to the San Francisco Bay Area press. These letters included four cryptograms (or ciphers). The Zodiac had five known victims in Benicia, Vallejo, Napa County, and San Francisco, between December 1968 and October 1969.