745 ILCS 10/4-102

Neither a local public entity nor a public employee is liable for failure to establish a police department or otherwise provide police protection service or, if police protection service is provided, for failure to provide adequate police protection or service, failure to prevent the commission of crimes, failure to detect or solve crimes, and failure to identify or apprehend criminals. This immunity is not waived by a contract for private security service, but cannot be transferred to any non-public entity or employee.