As David Fincher's outstanding 2007 movie Zodiac lays out meticulously and thrillingly, the Zodiac killer's identity has never been confirmed, and it seems that's how it will remain. Although the Zodiac claimed to have killed 37 people (through his multiple threatening, even taunting, letters sent to Bay Area press, complete with cryptograms), his official, confirmed body-count stands at five, all killed between December 1968 and October 1969.
The Zodiac's most shocking attack happened at Lake Berryessa, in Napa County, California, on September 27, 1969. Two Pacific Union College students were picnicking when a man walked up to them wearing a black hood (a la an executioner), sunglasses, and a white bib decorated with the now-Zodiac-dubbed cross-circle symbol. Claiming to be an escaped convict, the man ordered the woman to tie her boyfriend up with plastic clothesline, then tied her up and stabbed each of them numerous times.