Maureen "Mo" O'Grady is a Vice detective with the Mission Division of the Los Angeles Police Department. She is a corrupt detective and works for a ring of dirty cops controlled by retired detective Carl Nash.
Riley and O'Grady carry out the murder of Tony Allen on orders from Nash. O'Grady pretends to have broken down in order to cause Allen to stop his car, while Riley hides nearby. As Allen approaches O'Grady, Riley steps out and shoots him in the back of the head.