To release a mouse into the 'wilds', you have to drive them at least 2-3 miles away... otherwise the little buggers just come back, now that they've found a source of peanut butter. If you dump him in a place that has an alternative food source, he may fare better.

Of course, your local council may have its own eradication programme, it's always worth asking.. If they are a humane council, they will have an approved 'release' site.

Failing that, get a cat or two. That way you only find half a mouse.

LTS