I discovered late in the afternoon that one of my secret Lindt balls at work had been nibbled into and hollowed out.
At about half past eight this evening I was in the back room and saw a small movement near the toaster. When I looked closely I saw a small dark shape under the toaster. I lifted the toaster up and there it was just sitting there, a nonchalant, mousy brown mouse. I said to it quite loudly
"I can see you! Yes I can. I see you there."
... And it just sat there
Later on I was putting stuff away at the end of the night and it was still under the toaster. Its tail was hanging below the shelf against the wall. The wall mounted shelf is on brackets with about a 1cm or so gap between the edge of it and the wall. I knew it wouldn't be able to go anywhere or bite me if I were to get its tail. So I held it there, pressing its tail against the wall
My coworker was scared of it so we got my brother - who was there to come home with me - to bring me a plastic bag. We moved the toaster away. The mouse squeaked quietly and tried to move but of course it couldn't. I put my hand in the bag and did the dog poo treatment to the mouse - capturing it in the bag, turning the bag inside out, closing it shut. Then I did what my dad did to a mouse years ago*. I took that bagged mouse and gave it a solid whack against a hard object, killing it in one strike. I gave it a couple more just to be sure.
I left a note for my manager saying 'I caught and killed a mouse! It's in the bag in the bin.'
*We had left a wok of cooking oil to cool overnight. In the morning there was a small, sorry looking, oil soaked mouse struggling to get out, running up the side of the wok but slipping back in again. He poured the oily mouse into a plastic bag and gave it a hard whack against concrete step. Dead on the first strike.