The Vampire Bat（1933）

When the villagers of Kleinschloss start dying of blood loss, the town fathers suspect a resurgence of vampirism. While police inspector Karl Brettschneider remains skeptical, scientist Dr. Otto von Niemann cares for the vampire's victims one by one, and suspicion falls on simple-minded Herman Gleib because of his fondness for bats. A blood-thirsty mob hounds Gleib to his death, but the vampire attacks don't stop.