Krewson and O'Toole said in a statement that the St. Louis Police Department's internal affairs division and the civilian oversight board will investigate the police response to protests over the past nearly two weeks, during which more than 200 people have been arrested across the region and nearly three dozen officers injured. But they said a third-party investigation is necessary because it is "important that the public have confidence in the results of this process."
Email messages seeking comment from the U.S. attorney's office in St. Louis were not immediately returned.
The statement said police internal affairs have received a dozen complaints. The American Civil Liberties Union of Missouri has also filed a lawsuit accusing police of unnecessarily forceful arrests and rounding up innocent bystanders on Sept. 17, when about 120 people were arrested following an unruly protest downtown. Police drew complaints for a process known as "kettling" that confined protesters and others to a limited space. But some of those arrested, including bystanders and a St. Louis Post-Dispatch journalist, said they had nowhere to go when ordered to disperse.
Others have complained about officers chanting "Whose streets? Our streets," after the arrests, using a common refrain from protesters.
That protest was among several since Sept. 15, when Circuit Judge Timothy Wilson ruled that former officer Jason Stockley was not guilty of first-degree murder in the 2011 shooting death of a drug suspect, Anthony Lamar Smith.
The statement said St. Louis officers have worked long hours in "high tension situations" to keep demonstrators safe and to protect people and property.
"These are troubling and difficult allegations, and it is important to determine if they are merited and, if so, what policy, training or discipline issues need to be addressed," the statement said.
The protests have not been limited to St. Louis. Several people were arrested on Sept. 16 in the suburb of University City. And on Saturday, 22 people were arrested in another suburb, Richmond Heights, during a protest at the upscale St. Louis Galleria shopping mall.
Protesters, faith leaders and several elected officials have called for an independent investigation of the way police handled the Galleria protest, where those arrested included a female pastor accused of jumping on the back of a police officer, and a 13-year-old boy.
St. Louis County police spokesman Shawn McGuire said his department has not joined in the request for a U.S. attorney investigation. McGuire said the department has received no complaints from protesters involved in the Galleria arrests. But on Tuesday, several people spoke at a St. Louis County Council meeting and demanded an independent investigation.
It wasn't clear whether Richmond Heights and University City police would support a federal investigation. Phone and email messages seeking comment were not immediately returned.
O'Toole, speaking to KMOX Radio host Charlie Brennan on Wednesday, defended his officers, noting that 30 have been injured during the protest, including five requiring hospitalization.
One officer sustained a dislocated jaw, another suffered an injured shoulder and a third had a concussion, O'Toole said. Another officer had lung problems after being exposed to an unknown chemical, and another required stitches after being cut by broken glass.
Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.