The Man They Could Not Hang on VHS. Starring Boris Karloff, Lorna Gray, Robert Wilcox. Directed by Nick Grinde. 1939.
From the box:
Filmdom’s Master of Horror, Boris Karloff, stars in this thriller in which a brilliant scientist is transformed into an insane killer. Doctor Savaard, who has invented a mechanical heart designed to restore life to the dead, kills a student volunteer in order to test the device. Midway through the experiment, the police break into Savaard’s lab and discover the dead body.