A police officer who is acting as a security guard is not on duty and being paid by the municipality that he or she works for. However, under the laws of all states in this country, an off duty police officer is allowed to arrest a person much like an ordinary citizen as a "citizen's arrest".This seems to be what happened in your matter.Since you have a criminal matter pending, it is recommended that you consult with a criminal defense attorney about it before making a court appearance.