So you know those nice humane mouse traps you can buy, where the mousey runs in, the door shuts, and then you take it and release it somewhere, and you're full of warm fuzzy love?
I gave you a chance, mouse. It's kill, kill, kill from here on in.
(I'm guessing it went in there last night, and before we got up this morning had managed to EAT ITS WAY OUT. The little bugger.)