First of all I don't believe Peter killed his mother. She was alive when he left with his friend to play in the band. If I remember correctly in the movie his friend picked him up & either saw the mother or heard her say good by. Peter did not hate his mother. The police were just all over him. He had no one with him when they were questioning him. He had no lawyer, no friends or family member with him. They questioned him for hours. He was just a kid. They had no right talking to him with out a lawyer or some one with him. He was scared & upset. He had just found his mothers body. He had no father. In fact he didn't even know who his father was. He was lucky that he had people that cared for him & stood up for him.