515 ILCS 5/1-165
All authorized employees of the Department and all sheriffs, deputy sheriffs, and other police officers shall arrest any person detected in violation of any of the provisions of this Code, including administrative rules. Any duly accredited officer of the Federal Fish and Wildlife Service may arrest any person detected in violation of any of the provisions of this Code, including administrative rules.
All officers shall make prompt investigation of any violation of this Code, including administrative rules, reported by any other persons, and shall cause a complaint to be filed in case there seems just ground for a complaint and evidence procurable to support the complaint.
Upon the filing of a complaint, the officers shall render assistance in the prosecution of the party against whom complaint is made.
Peace officers, other than employees of the Department, making arrests and serving warrants provided for by this Code shall receive the fees and mileage as provided by law for sheriffs.
Each duly accredited officer and authorized employee of the Department is empowered to execute and serve all warrants and processes issued by the Circuit Court.
515 ILCS 5/1-165