Who is Justin Kearney from Black Friday and what is their importance?

The President of the United States at the time of the bombing, Kearney is working on the investigation. It's his decision that Carroll will handle only a portion of the continuing police work on the case while the authority over the case will be transferred to CIA Director Phil Berger, prompting to Carroll to briefly resign. As the case winds down, Kearney is handed the original document outlining the details of Green Band - written six months before the bombing. The details of the report aren't revealed but it's evident that the Committee of Twelve plan to have Kearney take the fall for the bombing and the subsequent stock market crash, allowing them to put Vice President Elliott, a member of the committee, in office.