Very good whodunit, with an intricate and icy logic worthy of Sir Arthur Conan Doyle himself! However, there is no delicate way of putting this, but the monster's instrument of death is a large wooden phallus! Not an implement one can imagine Professor Moriarty brandishing with a great deal of conviction!
Oh, if only! Sister of Ursula is a late giallo and is pretty much a softcore movie. It makes very little sense. I've watched it a few times and it's not even entirely clear how the killer gets the intended victim to stay still long enough to use the ridiculous weapon! Like all Italian stuff, it's very nicely shot, even elegant in places, plus the girls are v pretty. So it is more than watchable. The music is odd. Actually, it's comically similar to jingle bells at various points.
I found a copy cheap at car boot sale ("no you didn't you liar, you paid far too much for it"). And though not great, you would have to cut my hands off to part me from it. It's just one of those films that the act of merely owning a copy causes spasms of nerd pleasure.