Is there a limit to the questions an officer can ask a citizen when he does not have probable cause? For example, he drives through the parking lot of a local mall, sees a citizen exiting a vehicle which is similar to those drive by police. The citizens vehicle has no external markings on it, yet the officer (in plain clothes and a marked card) asks the citizen their name, where they live, where they got the car etc. Ending his remarks with "we've had a lot of used squad cars purchased by the public, and it's becoming a problem." The citizen was not written any tickets. No warnings. Nothing. Just stopped and asked the questions above. Can they detain you and ask questions for their own curiosity? I seriously doubt he was looking for a similar car used in the commission of a crime because he didn't ask any questions related to that type investigation.