The St. Louis County Police Department was established on July 1, 1955. The department was created with 95 officers and 18 civilian employees. The department is divided into four divisions: Patrol, Operational Support, Special Operations, and Criminal Investigation. It is the third largest local police agency in the state and one of two
county police departments in Missouri, the other being the
St. Charles County Police Department. The SLCPD is accredited by the
Commission on Accreditation for Law Enforcement Agencies. CALEA is the only international body that accredits law enforcement agencies. Only seven percent of all U.S. law enforcement agencies are accredited. In 2010, CALEA recognized the St. Louis County Police Department with it distinguished Tri-Arc Award. The Tri-Arc Award is reserved for those police agencies that have successfully accredited their law enforcement services, police academy and communications division. Only six agencies in the world have achieved this status. Starting in October 2018, the St. Louis County Police Department began patrolling
Kinloch after it dissolved its city police department. On October 25, 2019, a jury awarded $20 million to a police sergeant for discrimination by the St. Louis County Police Department. Witnesses testified that police department leadership had said that the sergeant would never be promoted because he was "way too out there with his gayness and he needed to tone it down if he wanted a white shirt." (The command staff are called "white shirts" because of the color of their uniform shirts.) On October 27 County Executive Sam Page announced that "the time for leadership changes has come and change must start at the top" of the St. Louis County Police Department. After reaching the settlement, Chief Jon Belmar resigned from his position. It is unclear if insurance would cover the amount.
Fallen officers From October 4, 1871, to December 1, 2021, the Officer Down Memorial Page reported that 13 officers in the St. Louis County Police Department died in the line of duty. ==Board of Police Commissioners==