Had a US Marshall at my door telling me my friend was a wanted suspect in child sexual abuse case. My first reaction was nope wrong guy. Even the photo they showed did not look like him. Told the Marshall when he arrives I will call. Told my friend that the Marshall was in town for him. His immediate response was that he and the girl are in love and it is okay because he was adopted so it is not really his niece. That was the end of that relationship. Our role is to not protect the molester or abuser but protect the people they may harm. Saying nothing and doing nothing will saddle you with immense guilt. Your friend is a scumbag and over 21 having sex with 14 is terrible. Doesn't mean he will be attracted to his daughter but I would not rule out her friends. You did the right thing.