To Love, Honor and Deceive (1996)

Sydney Carpenter was happy as a housewife devoted to her husband Matthew and their little boy Adam, till they both die in a boat accident. Shortly after she's irritated when local PD Det. Jim Sanders tells her probably nothing can be done, but soon she finds him most helpful, especially after FBI Special Agent Kyle Lassiter insists he walks away from the case. They dig on as she is the target of more criminal visits, discovering Matthew had a dark past and got into the witness protection program, but are told that his staged accident actually killed him...