Problems with stupid brother in law, serious only please...?

Okay, so here is my problem..Please don't answer till you read the whole thing. My brother-in-law is a convicted felon, who is a alcholic and does drugs. He also deals. He has lived in my mother in laws house now for around 6 years stealing her blind. She always takes up for him. He does no wrong and my husband does no right. Well, around six months ago, some child molestation charges were brought against him as well as many, many others. My mother in law says the child molestation charges were dropped as well as a few others. He was allegedly molesting his two daughters (15, 13) She said they talked to DHS and said it was untrue. My daughter told me that the oldest one said that they were being molested and that they would never tell the truth cause he was the only parent they could live with. (mom is in florida and a hooker/drug user/stripper). But this is two year old info we just found out. Shoud we turn him in or what? We are in very bad situation.