Forensic psychiatrist Dr. Helen Morrison shared intriguing data about serial killers, whom she's extensively profiled over the last 25 years. Typically, neighbors and relatives are shocked to find out that someone they know is a serial killer, she said, as the person doesn't give off any external clues. John Wayne Gacy is a perfect example of this, she added, as he acted neither suspicious nor crazy.Mass murderers have motives such as revenge, Morrison explained, but serial killers commit their heinous acts without motive or emotional meaning.From her studies, she has concluded that serial killers do not become the way they are from any particular traumatic incident. Rather, she believes they have a genetic predisposition for this and that something occurs during adolescence that triggers their brain chemistry. Usually, they first kill as a teenager, and then wait for a period before committing another murder, she detailed. The behaviors and mindsets of serial kill ... More »