Long before the era of young people committing mass murder became a too-common event, sixteen-year-old Harry Hebard made world news when he killed all five members of his family in Kennedy-era Green Bay, Wisconsin. Harry appeared to be a relatively normal teenager. A member of the high school track team, Harry harbored a deep resentment that would make its ugly appearance on a cold winter's day in 1963. In systematically executing his family, Harry became the first documented teenage mass murderer in Wisconsin history. Criminal profile veteran Steve Daniels details Harry's case and provides insight into what makes Harry and other mass murderers tick.