[M.D. Holloway]

Every so often a boy form 2 houses down comes over to play - I always ask him if is Mom or dad know he is here then I call them up and tell them he is at our home and he is fine and welcomes for X hour(s) until we have to do whatever. When he is done playing or Our Son is done with him or when we have had enough, I walk him home and let his folks know he was a great kid and we enjoyed having over.

I don't know if it would work for your intruder but it seems to work pretty well in our case.