Early Serial Killer flick

Most definitely a B movie, but, not without interest. One of the early serial killer films, and there are more than a few precursors to elements in SEVEN, SILENCE OF THE LAMBS, ZODIAC and even a Roger Corman 90s cheapie THE RAIN KILLER (photographed by Janusz Kaminski!).

Any other early Serial Killer movies that folks can cite outside of the various takes on Bluebeard and Jack the Ripper?