Instinct to Kill (movie, 2001)

Escaped serial killer James Becket, who killed his own father whose expectations he never fulfilled, but now especially targets his wife Theresa 'Tess' and her family, is too good at disguising himself and other deceit for detective Diffs task force. Only one man proves able to fight back in his league: former cop J.T. Dillon, who was already training Tess in self-defense and becomes her lover. Becket decides to find hiding place by kidnapping Diffs wife, and thus enforce a final show-down.