If you don`t want to kill the little thing(s), buy a "humane" mouse trap & then let them go in a field or park. If you don`t get rid of it/them you will be soon invaded & they`ll breed in the house, especially with the cooler weather coming. When the building next door was demloished, they got in by way of the 3rd floor of our house!! They kept waking me up in the middle of the night. I know it`s illegal to release trapped squirrels elsewhere, but not sure about mice & rats. Best not to tell anyone what you`re up to if you go this route!