Used Cars: Used cars and titles, small claims court, duplicate title

Question
I just recently bought a used car from an individual.  I said he could keep the motor since I was going to replace it anyway.  He took my cash money, signed the title, gave me the title, then delivered the car to me at my house on a trailer.  Two days later there was an altercation resulting from my schedule not allowing him to remove the motor as quick as he wanted.  Two weeks later when I went to transfer the title to my name, he had already gotten a duplicate title issued which makes the copy I have worthless.  Wouldn't this be a criminal offense on his part and who should I report it to if the police are doing nothing to help me?

Answer
Well my first question would be, did you get a signed bill of sale, when you made this purchase?  If not, I am not sure how much you can do.  If the police are unwilling to help, it is probably because they know there is not much can be done.  If that had happened here in Oklahoma, I would tell you to call the Used Motor Vehicle and Parts commission, however, pending what state you are in, there may not be such a place.  Oklahoma is one of a very few that have something like that, but even then, I dont know what they could do in this situation, because they deal more with dealers, than individuals.  Your only other option may be small claims court.