@14

"...can the police issue a court order to the ISP used (which i also have) to obtain the exact physical address?"

You can turn over the information to the district attorne's office to see if they would be interested in pursuing the case.

If the D.A.'s office is not interested, file a civil suit naming the defendant as a Doe until you can ascertain the name. Then, you can issue your own subpoena to the ISP to find out the physical address and the name of the person who owns the account.

Keep in mind, if the D.A. is not interested, it can be very costly to file a lawsuit, even without an attorney, although if this is an item covered by a small claims action, then you can do it in small claims court and it won't cost as much.