If it was all the loose ends were tied up nicely at the end, I don't think it would have worked. As it was you never really knew what'd happened when he was a kid.
Shame about Cassie getting together with Sam instead of the main guy. Though you can see why really!
Was a bit unlikely I suppose that he would have made it into the police force. Presumably they do checks on backgrounds...
Overall, tho, a really page-turner, very enjoyable.