Pevert

First, I would be sure that you are right and if we are talking about an underage girl then I would call the police or a social worker. If she is not under age then you could confront him about it and tell him that it is wrong and/or talk to the girl and tell her it is wrong. Even if she is not legally underage he could be forcing her to do so. In any case, they may be angry and/or ashamed that you know and may stop speaking to you. You could approach his wife, if he has one or the girl's mother and tell her what's going on. They will likely be angry with you but really are you going to stay friends with someone who would do that, if you have children you couldn't trust him anymore. Whatever yo decide to do, you should do it right away.

Go to the police and then confront him and tell him you've reported his activity to the authorities. Tell him how you feel about what he is doing. It might also be good to see what you can do to see that his daughter gets help. She's been through a lot.

If this is true you MUST report it immediately. You can't sit by and allow it to continue. If you do then you are just as guilty as the SICKO that is doing this to his OWN daughter.

okay so I'm just putting this question out there but... is incest illegal if both parties are over 18? So it might be legal and just disgusting and unbelievable to most people. okay if it is illegal and especially if the girl is young you should tell the police otherwise maybe if the man is married tell his wife or the girls mother you may not find it your place but I think if you know you should deffinately do something I would.

Whatever the situation is, whether the daughter is an adult it's still incest and it's a sin to rape your own child even relative. You should talk to your best friend and have the issue iron out. If he refuse then it's time to tell the authorities about it.

Report to the police. Confront him. Thats the worst thing that can ever happen to a girl. Especially if its her biological father. Tell the locals about it ok.

Call the cops!!! This is disgusting and horrible! Your friend needs some serious psychological help. How old is his daughter!?!?!