It’s the world’s worst spree killing. Discovery Channel Norway Massacre: The Killer’s Mind examines the terrible events of that day. In 90 minutes of madness, 32-year-old Anders Behring Breivik killed 69 young people. The film pieces together Breivik’s day of terror hour by hour, from the time of the bomb he set off in Oslo, to the cold blooded shooting of defenseless youngsters on the remote island beauty spot of Ut