How do you catch a serial killer who picks his victims at random, and whose only motive is to taunt the police? In Part 1 of this 2-part investigation into California’s Zodiac Killer, I’ll present the story of one of the most bizarre yet compelling unsolved cases in criminal history. Coincidences, letters, ciphers, phone calls and costumes – they’re all here. Join me again next time for Part 2 where we’ll do some more analysis and a review of the suspects.