Re: I saw a mouse
Reportedly, a mouse released anywhere near the premises it was removed from will head straight back in. Co-existence is achieved only by killing them, modern easy-open snap traps checked daily being recommended, baited with peanut butter, chocolate spread, or manufacturer's patent which may be just one of those but don't taste it. The traps are not easy-open if you're a mouse and/or dead. Poison means that you now have dead poisoned mice hidden all over the place. And the poison, the dead mice, or traps may be bad for other pets.
I've occasionally had mice get away from the traps, and one survivor bleeding from his injuries. Lively though. I did take him for a walk in the dark around the corner, in the trap, let him go, and I think that was it for a while. I wasn't going to a vet. "Humane" killing needs consideration: dropping a paving slab on the poor chap is one suggestion. The survivor might have had a worse night (or not) if I'd had another idea; since he was captive in one trap, I could drop him onto another trap, snap.