The cop said that I should expect him by Monday but refuses to say why. What should I expect?

The security officer (who is also a deputy police chief) at my old neighborhood busted my roommate for Schedule 1 controlled substance possession, and myself and my other roommate also got charged. I'm set to see a judge to begin probation next week. Now I live in the adjacent neighborhood and my neighbors had a party that got busted by the security officer from the old neighborhood, some people ran and some arrests were made. I wasn't even at the party, but the officer told me to expect him Monday with some paperwork, and when I asked refused to tell me what it’s all about. I’m under 21 and was drinking last night, but not at the party.