the night caller (1965)

aka Blood Beast from Outer Space. Bloodbeast from Outer Space. Night Caller from Outer Space.
Starts as your typical sci-fi, with a mystery object spotted over London. It lands and is being investigated by Ministry of Defense scientists when
mysterious things start to happen, and an inhuman presence makes itself felt before escaping. Subsequently the film flips into a detective noir, as young women start disappearing, and the scientists and police both try to hunt a mysterious killer down.
A gem of a film that showcases the fact that a low budget does not necessarily mean a low rent film.