That's a big mouse. Like someone else said, there's probably more around. How much did you pay that guy to tell you that you have mice
I don't know the name of them, but there are these mousetraps that are easy to set(you just sqeeze the end, they look like a clip), not the traditional ones, put a little peanut butter on them and mice just can't resist. They have a big V on top of them. All my kittens are gone or i'd offer you one.