It Turns Out The Hot Psychologist Was The Killer; Just My Luck, Just My Luck

I'm not ashamed to say that I'm a fan of Conan that Japanese anime series. (Because as hard as I try, I can never guessed the killer and I tried to analyze pretty much every scene in one episode but the ONE thing I didn't see ends up to be the clue to the whole she-bang.)
And oh my nohs, the killer was the hot psychologist. WHY? JUST TELL ME: WHY?