Mouse in my study

I have no issue whatsoever with mice if they stay outside where they belong.Sat down to do some writing in my study bout a week ago and heard a rustling behind one of the book cases so thumped the wall noise stopped problem solved I thought.Next evening I was just about to sit down and do some blogging when I noticed a piece of notepaper that had somehow ended up in the corner,said piece of notepaper had obvious chew marks in it and was surrounded by the torn remnants of the mices meal.As I said no issue with them if they stay outside they are not at all welcome anywhere near my library. Took action laid some baits down and entered study 2day to be greeted by a smell that can only be described as a dead mouse wish it had gone back outside to die agggggggggg