I was watching one of the crime shows last nite, and an expert was talking about asphyxiation. It was said that a person can become unconscious very quickly when pressure is put on the neck area. Supposedly, this can lead the killer to let go, thinking the person is dead. When the victim gains consciousness, he is strangled again longer until dead. I wonder if this could have anything to do with the extra, lower cord mark on Jon Benet's neck?