That Obscure Object of Desire could be an alternate title for Vertigo. At the end of that film, it will be remembered, Scottie stares into the abyss below (and without vertigo). In the dark he can only look down on nothingness--the essence of Madeleine, a woman who never existed. No object could be more obscure.
I think you have to nominate yourself for the Ebert award for Feb.
Psycho and The Diary of a Chamber Maid both involve a sex killing.