Mumford has left - I think. I hope.
A guy at Home Depot told me about an ingenious trap, which I set and left out over the weekend to no avail.
The trap works like this: you take a tall kitchen trash can and in the bottom put a bag of popped popcorn (I chose cheese flavored) and some peanut butter. The mousie climbs in, eats itself silly, and can't climb out. Then you take the trash can out to a nice field somewhere and turn the mouse out in the wilderness, full and unharmed.
Mumford didn't take the bait, and I have it on good authority that he likes trash.
So I think he's gone. Will keep you posted.