You have someone on your property moving survey markers and digging things up. You call him? You should be face to face dealing with this. The one thing that could be in his favor is he is working within the city, state or county utility right of way which is not your property. I know on my county road it is 33 feet from the center of the road. I would find out and then deal with it. Once past the right of way he has no business on your property.