What should I do? I am a victim of grand larceny and the police will not help!?

About one week ago, I had lost a very valuable scarf made of rare mink, and filed a police report with details from the incident. It is valued at $1000 by a fur dealer who appraised it (it is a valuable family possession, now lost). In New York that is considered grand larceny (amounts over 1000) but was originally written up as Petit Larceny, and not sure if they changed it after I told them the amount. I had dropped it and one person stole it off the ground. I confronted them and they ran away to take a cab home. I have the cab license number, and all cabs here have GPS in them, as well as option to pay with credit cards. It is easy to find out where the person lives based on the GPS, finding the driver from the medallion number, and if they paid by credit card, their name would appear. Then they could search their place, plus any surveillance to identify the people in addition to my description. As far as I know to this point it was NOT assigned to a detective, and the police said they will not do anything about it anymore. WTF! What do I do? They said I can come in and talk to a supervisor....like that is going to help. I feel this was handled very poorly and with a little bit of work, it is possible to find these people. help!