Beyond a Reasonable Doubt is a 1956 film noir directed by Fritz Lang and written by Douglas Morrow. The film stars Dana Andrews, Joan Fontaine, Sidney Blackmer, and Arthur Franz, and was the last American film directed by Lang.
Tom agrees to the plan, not knowing that unforeseen events will put a snag in the scheme. Spencer dies in a car accident before he can testify, and photographic evidence intended to clear Tom at his trial is burned to an unrecognizable state. Tom is found guilty and placed on death row in prison. A written testimony by the dead man is found in time to prove the two mens intentions, and Tom is to be pardoned.However, a slip about the late womans real name to his fiancee Susan Joan Fontaine, leads him to confess. Patty Gray, the murder victim, is actually Emma Blucher, Tom Garretts estranged wife, who had reneged on her promise to divorce him in Mexico. As this was preventing Garrett from marrying Susan he murdered Emma. Garretts pardon is cancelled in time to prevent the double jeopardy rule coming into effect, and the film closes with him being led back to his cell. We are given to assume that his execution goes ahead as scheduled. ........
Source: Wikipedia