Like a predator, Ferris had singled out their weakness. Hanging out in the park where children often played, he read their situation and then struck up a conversation with the mother when she had trouble starting her car. Could he help her? He knew something about engines. He fixed some loose spark plug wires. Later, investigators couldn't say whether Ferris had pulled the wires in the first place.

Another evening he showed up with food and treats for the girls. Another time he gave them all a ride to the grocery store. He made himself familiar. He made himself look safe.

Nick remembered the interviews he'd done with teachers and the principal of the elementary school, their recollections of the girls, how bright and eager they were to learn and be with the other children. The way the older one was so protective of her sister. The description of what they were wearing on their final day.

As the girls were walking to the park which they now considered home, Ferris pulled alongside in his familiar truck. He told them their mother had gone out to look at a house they might move to. He said she'd asked him to give them a ride. Maybe the girls were reluctant, but they knew him, had ridden in the truck-with their mother-before.

Ferris took them to a small house less than three miles from the park. He knew it was the younger girl's birthday and promised a cake. But once inside, he molested the six-year-old in a bedroom. When she began to cry, her sister came to her aid. Ferris killed them both and then hid their tiny bodies in the attic of the house. When they failed to show up at the park, the girls' mother went to the school and police were called. She immediately identified Ferris as a man who had befriended them. It took a day for detectives to track him down. They found him in the small rental house and interviewed him for an hour. They read him like a book and returned the same afternoon with a search warrant.