Clues

 

There was a lingering scent of moron in the room, so I knew you had just been there, not to mention your annoying habit of eating avocados and spitting out the pits.   Your fingerprints were all over the ends of your hands and it was your shade of lipstick they found on your own collar.

As you can see, I can't stay serious long enough to write a who-done-it.

ZC