just give it back to your cat. mouse is a no no in the house. you will get bigger problems if you let it loose.
Let him outside of course but for the other wolf pack of them if my cat that actually likes mice and doesnt run away from them goes at it im allowing it to play with it for as long as possible
Buy a cages in put him there, Also buy him a playmate. hehehe. like a white rat. I have caught a rat I will Do some expirement if it can be friendly to human.