Top 10 Unsolved Crimes

"I like killing people because it is so much fun."

So began one of the many encrypted letters sent to San Francisco newspapers by the man who called himself the Zodiac. For most of 1969, a serial killer terrorized Bay Area residents, killing five and possibly more. It started on Dec. 20, 1968, when a couple was shot to death while sitting in a car on a lover's lane. The killer would strike several more times over the next 10 months, shooting a couple in a public park, trussing up and stabbing yet another man and woman near a peaceful lake, and shooting a cabdriver in the head.

What made the case so fascinating, though, was the way he toyed with police and reporters. He called in several of the murders and began to send coded letters to newspapers, using a cross within a circle as his symbol. At one point, he mailed in a piece of bloodied shirt to prove he was who he claimed to be. Another time, he threatened to shoot up a school bus full of children. The investigation went on for years. Several suspects were considered and questioned, but to no avail. The Zodiac was never caught. The story continues to terrorize people to this day (see David Fincher's masterful 2007 film).