Hi each state has its own procedure for issuing the police certificate. Even if you don't live in the states anymore you need a fingerprint card filled and signed and the proper fee and to send it via mail to the concerned party. the following link has info on all states !
http://www.canadavisa.com/canadian-immigration-state-police-clearance.htmlI sent mine a month ago and I am still waiting i lived in texas for a couple of years!!
Good Luck.