Last night a gunman shot and killed 12 people in a California tavern. The gunman was also killed. Interviews with law enforcement have stressed that they will work very hard to understand the gunman's motives.
As the gunman is dead (hence unable to be prosecuted), what is the value in understanding his motives?
It is reasonable the LE would want to determine that the gunman "acted alone", but why is it important to understand a dead gunman's motives.
( not your typical Law/se board question, but it surely doesn't belong in Politics/se)