The voices in Bobby’s head told him to do things.
“Clean your room,” they said.
So, Bobby cleaned his room.
“Mop up the mess in the kitchen,” they said.
So, Bobby mopped up the mess in the kitchen.
“Make the back yard took nice,” they said.
So, Bobby bought plants and grass and flowers, and he planted them.
The voices walked Bobby through a list of chores, and Bobby dutifully did them all.
By the time the police arrived, there wasn’t a single shred of evidence left that he’d killed his parents.
Just as the voices told him to do.