One of the larger changes is that Mary, after killing her husband, trashes her house so it looks like there had been a fight. (In the film) In the story she just pretends that she came home and there he was. Which I mean messing up the house was a rookie mistake! The only fingerprints would have been hers and the room looked its part but the only wound her husband had was a head injury. This was a important change that led the officers to have better guesses, but it wasn't the most realistic The last small difference is that she called her friend to help build up her alibi. That was a part that defiantly improved the film and would have improved the story if it was