A federal investigation will look into possible civil rights violations by police in the St. Louis area in the two months since protests broke out after a white former police officer was acquitted in the shooting death of a black suspect.

The U.S. Department of Justice announced the investigation in a statement Monday. The FBI and the U.S. attorney’s office in St. Louis also will help with the investigation.

Protest leaders, Democratic U.S. Rep. Lacy Clay and others called for a federal investigation. More than 300 people have been arrested at protests since Sept. 15, when a judge ruled that Jason Stockley was not guilty of first-degree murder in the 2011 death of 24-year-old Anthony Lamar Smith.

Several of those arrested have alleged heavy-handed arrests and even taunting by police.