What should we do regarding a man who fondled his niece until she became pregnant by him, then he aborted her out of fear of scandal?

Adultery is a grave sin (kabirah). If it is committed with the wife of a neighbor, it is even more heinous and criminal, second only to disbelief (kufr) and infanticide. Adultery with a mahram (a person with whom marriage is forbidden due to close kinship) is the most reprehensible and atrocious, and its perpetrator is punishable by death. Abortion is taking a life, unless the mother's life is in danger. If the matter becomes public, it should be referred to the Sharia court. If it does not become public, it is advisable to conceal it, repent, and seek forgiveness. The expiation (kaffarah) for killing the fetus and its blood money (diyah) become obligatory if the abortion occurs after forty days.