Happy Face Murders (1999)

An eccentric older woman (Ann-Margret) implicates her brutal & controlling lover in the murder of a young intellectually disabled girl. Absorbed with "Murder She Wrote" and "Matlock", she creates details of the murder from clues she picks up from the detectives (Marg Helgenberger, Henry Thomas) on the case. Implicating herself and sentenced to jail, she then recants her testimony. But no one believes her until clues surface from the real killer that he is still out there, has killed before, and will kill again. He signs his messages with Happy Faces.