Before I Hang (1940)
Before I Hang is a 1940 American horror film starring Boris Karloff. It follows Dr. John Garth, played by Boris Karloff, is sentenced to death for performing a mercy killing. While on death row, he continues his research on a serum to reverse aging, but after testing it on himself, he becomes younger and develops violent tendencies, leading to a series of murders before ultimately confronting his fate.