Complaints against CPD officers are routed through several investigative bodies. Most complaints are investigated internally. Minor allegations are investigated by an officer’s supervisors, while more serious complaints are handled by the CPD’s Bureau of Internal Affairs. Some types of serious complaints, including use of force, racial slurs, and domestic violence are investigated by non-police investigators. Beginning in 1974, these cases were handled by the Office of Professional Standards (OPS), which employed civilian investigators but was still part of the CPD. After a series of police scandals in 2007, OPS was replaced with a new civilian agency, the Independent Police Review Authority (IPRA), which operated outside of the CPD. In September 2017, in the wake of the killing of Laquan McDonald, IPRA was also deemed ineffective and replaced by another civilian oversight agency, the Civilian Office of Police Accountability (COPA).