I don't know about those particular plates since I am no longer LEO and anybody who looks up those plates are in violation of abuse of the NCIC/CCIC database and can get fired as well as loose their future ability to use the system.

Many municipalities have their own LEO vehicles and can and do register them as city vehicles.

There is no set of numbers or pre-fixes on plates that indicate a LEO.

On a side note:
Under cover officers like vice get a plate that is truely not related to LEO and they have a cover ID and address and name are all ficticous yet will have a history. This is because if you are a criminal and have a LEO friend and they look up a plate or identity id does not come back to a LEO. Unfortunely some cops are dirty and some cops are guilt of helping criminals without consent.

Is this what you are up to?