The Devil Bat (1940)

"The Devil Bat" is a (1940) horror classic movie.
A scientist (Bella Lugosi) creates a giant bat to kill people. The bat is controlled by a special scent that only the scientist can produce. The scientist uses the bat to kill people who he believes have wronged him. The police are called in to investigate the murders, and they eventually discover the identity of the killer. The killer is arrested and the bat is destroyed.