As additional suspected victims were located, a profile began to emerge, according to people with knowledge of the investigation. Sandusky engaged in what experts on child predators call grooming behavior, law enforcement officials asserted this month, making his first approach when children were 8 to 12 years old. He tended to choose white boys from homes where there was no father or some difficulty in the family, investigators said, and he drew them in with trips to games and expensive gifts like computers.