Complex sentence: It was finally solved when the BAU found that a mentally handicapped carny clown had committed the murders accidently when he broke into the house to play with the oldest daughter, the father surprised the man in the parents' bedroom and triggered the resulting attacks.
Split into simpler sentences: It was finally solved when the BAU found that a mentally handicapped man had committed the murders. He had broken into the house to play with the oldest daughter, the father had surprised the man in the parents' bedroom and triggered the resulting attacks.