Amy Kern, left, said she drove 400 miles overnight to Port St. Lucie to kill her father because he was Satan and she was Jesus.
When she couldn't find him, she started down Interstate 95, shooting at vehicles.
She then decided she needed to kill her grandmother, but first she stopped at her aunt's house.
She fatally shot her aunt's boyfriend, William Chapman, 59, before continuing to the home of her grandmother, Donna Kern, 80.
She beat her grandmother - who fought back - with a tire iron.
Family members said Amy Kern is bipolar schizophrenic, who suffered from post partum depression after having a baby.
She had tried to check herself into a mental hospital in Georgia after midnight on Saturday.
The Palm Beach Post has the story.