It seems so strange that some hasn't' found him yet. I'm only guessing he's friendly and would approach someone if he couldn't find his home.
How far away from you does this girl live? If it's in the general vicinity I would think it's definitely plausible she could have him. I would go back to the police and this time say you strongly believe she has him. That way they would be required to follow up on your complaint.
Since this girl is the only lead you have - - I'm praying for you it's the answer you're searching for.
__________________  My dog's not spoiled, I'm just well-trained |