Killer was 'angry at life, angry at God'

(CNN) -- To his wife, Charles Carl Roberts IV was "loving, supportive, thoughtful."

To his co-workers in rural Pennsylvania, Roberts was a milk truck driver whose mood had darkened in recent days.

To himself, he was a ticking time bomb, consumed by a mysterious grudge that he had harbored for two decades.

And to five young Amish schoolgirls on Monday, Roberts was judge, jury and executioner.

Now the 32-year-old man is dead, his last act a final trigger pull with his gun aimed at himself. He died on the schoolhouse floor, surrounded by the bodies of his young prey.

The reason for his rampage may have died with him.