Someone went through my car claiming it was stolen. I had checks w/ my ssn # on them in the car. Advice?

I live three hours away from my girlfriend. I was visiting her and while in town we ride around in her car instead of mine. My car was parked in the same spot, in front of my girlfriend's house, for three days. One of my girlfriend's neighbors went through my car to find out if he could figure out if it was stolen or abandoned. I have three checks in the car with my social security number on them. The man that went through my car called my mother (who the car is registered to) after he found my registration, she then called me later that day. He told my mother his name and my girlfriend says she thinks he was a convicted felon. I called the police, my debit card company, credit card company, and equifax to 90 day red flag my SSN. Does anyone have any advice for what I should do from here?