Characters involved: Human male NPC (appearance/life details are up to you)
Evidence: Common hunting knife used. No fingerprints, fibers, etc., left behind by killer. No witnesses, either.
Body in Xanadu (location details are up to you). Throat slashed with single stroke. Nothing unusual about amount of force used (Luke purposely held back to make it look like another human did the deed). Wallet and pockets gone thru/money missing (staged mugging).