Three lawmakers have called upon Attorney General Eric Holder Jr. to take a larger role in investigating the shooting death of an unarmed teenager by a police officer in Missouri.

Reps. John Conyers, D-Mich., Marcia Fudge, D-Ohio, and William Lacy Clay, D-Mo., wrote a letter Monday asking the U.S. Department of Justice to investigate any pattern or practice of police misconduct of the Ferguson Police Department.