Chicago Mayor Rahm Emanuel asked the offices of the U.S. Attorney and Cook County State’s Attorney to launch a hate crime investigation Sunday after racial slurs, including the n-word, were heard on police radio channels last month.

The Chicago Police Department began an internal investigation March 14 after learning of an "inappropriate transmission on a police frequency," authorities said. According to Emanuel and the police department's Office of Emergency Management and Communications, the transmission was made not by a police officer but by an "unauthorized private citizen."

Audio from calls made on March 13 reveal a man saying "typical f---ing n-----s" on the radio channel as a dispatcher and officer communicate. Someone says in another transmission, "All black lives matter man, f---ing n-----s."

An officer on the channel asks the dispatcher to find out whose radio the comments came from but the dispatcher says she can't track it down.

"You know we don't do radio numbers, but I'm already hollering for my supervisor," she said.

In a formal request made Sunday to State's Attorney Anita Alvarez and U.S. Attorney Zachary Fardon, Emanuel said similar incidents have occurred since those calls were made public.



"In subsequent days, there have been at least three additional instances of one or more unauthorized users broadcasting racial slurs over CPD radio frequencies," Emanuel wrote.



Emanuel also said the broadcasts were not made from a police officer or on city equipment, a position the OEMC has maintained since shortly after the calls were made public.



"Subsequent investigation has indicated that the transmission was made by an unauthorized private citizen using non-City issue equipment," Emanuel said in the letter to Alvarez and Fardon.



"The audio in question lacks identifying characteristics of an official police radio," OEMC said in a statement following the March 13 calls. The department also said that any officer involved in making such statements would be disciplined.



"The language used does not represent the values of our police department or our city," Emanuel's letter reads. "These actions merit serious investigation as a hate crime or other applicable offense under Illinois or federal law."



The request for a hate crime investigation comes amid continuing tensions and fallout after the release of footage showing the fatal October 2014 police shooting of 17-year-old Laquan McDonald.