History's Greatest Mysteries: Season 4, Episode 2

4 - 2: Who is the Zodiac Killer?

In 1969, one of history's most elusive serial killers terrorizes Northern California. He taunts investigators with cryptic ciphers and clues, leaving police and the public questioning his identity for over 50 years. Can new evidence and technology finally crack his code? Who is the Zodiac Killer?