The 10th position in the VIN is the year. A "P" in this spot would indicate a 1993 vehicle, "R" would be 1994, "S" would be 1995, "T" would be 1996.
The 8th position indicates engine option. ONLY 1994-1996 Caprices have an LT1 available as an option, which would have a "P" in this spot.
Whether or not it is a police package vehicle can be determined by the SPID sheet attached to the underside of the trunk lid. If it is a factory police package it will have the code "9C1" on this label. You could also run the VIN number at a GM dealership to find the SPID codes, but just looking at the VIN itself will not tell you whether it is a 9C1.