A California panel denied parole for serial killer Charles Manson on April 11, 2012 and scheduled the 77-year-old's next parole hearing to take place in 15 years. Here's a look at other notorious serial killers.
Zodiac Killer. The crimes of the Zodiac Killer remain unsolved more than 40 years after they occurred. He killed five people in Northern California from 1968-1969 and sent a series of cryptic letters to newspapers taking credit for 37 murders, but police have never found out his identity.