The Killer Is Loose (1956)

A savings-and-loan bank is robbed; later, a police wiretap identifies teller Leon Poole as inside man. In capturing him, detective Sam Wagner accidentally kills Poole's young wife, and at his trial Poole swears vengeance against Wagner. About three years later, Poole (until then a model prisoner) abruptly takes his chance to kill a guard and escape. It's clear during the ensuing manhunt that Poole is obsessed in pursuit of a single end; but not quite the end everyone supposes.