Ok, will take a stab at this one....
Could be related to Project Safe Neighborhoods 'PSN', a Fed/DOJ juvenile gun related crime reduction program and has a database named RISS or Regional Information Sharing System. Makes sense in your neck of the woods. The troops might have been instructed not to use the RISS on the air or in reports in an attempt to keep its existence quiet and away from defense attorneys prying eyes.
Then again, in Alameda County California a PFN is a Personal File Number which is a three-letter/three-number file generated by the countywide booking system named CORPUS. Often used as source of information and at times one could find warrants that had not been entered in PIN/AWS/NCIC in error.
Could be one of these or who knows,,,,,let us know what it turns out to be.
And for whatever it is worth, your location was kinda unclear to me also, i went to look for a Lafayette County based on the lower case 'o' in your location. 'Co.' is a proper abbreviation for county, CO on the other hand would clearly say Colorado to me anyway.
Happy monitoring!
Regards,
Mike