( KTRS ) Illinois Attorney General Lisa Madigan has asked the U.S. Department of Justice to investigate whether the Chicago Police Department’s practices violate federal and constitutional law.

Madigan says that the “shocking death” of 17 yr old, Laquan McDonald, who was fatally shot by white police officer in 2014, raises serious questions about the use of lawful and excessive force. She says trust in the police department is “broken.”

In a letter to U.S. Attorney General Loretta Lynch, Madigan noted four other high-profile cases in Chicago, including the death of 25-year-old Ronald Johnson, who was shot by police last year.

Madigan says an investigation by the U.S. Justice Department’s civil rights division is “necessary and appropriate” because of its experiences looking into police department practices nationwide.