A 2003 study by Northeastern University researchers James Alan Fox and Jack Levin found that only 3 to 4 percent of all acts of homicide involve multiple victims.

It’s impossible to rule out that an ordinary person might someday commit extreme, irrational violence. But in most cases, a seemingly normal killer probably isn’t really as normal as he might seem, explains Dr. Alan J. Lipman, a licensed clinical psychologist and founder and director of the Center for the Study of Violence in Washington, D.C.

Discovery News