Hunt the Man Down (1950)

Dishwasher 'Bill Jackson' thwarts a robbery; resulting publicity fingers him as the 12-years-missing Richard Kinkaid, wanted for murder. Kinkaid half-convinces public defender Paul Bennett of his innocence; but Paul knows he'll never convince a jury without the 7 witnesses who've had 12 years to vanish. It develops that these prosperous young folks have gone down in the world. Paul and his father, a one-armed ex-cop, have a week to find them.