This undated photo provided by the U.S. Attorney’s Office shows Omar Ameen, who had been living in California as a refugee and was arrested Wednesday on a warrant alleging he killed an Iraqi policeman while fighting for the Islamic State.

This undated photo provided by the U.S. Attorney’s Office shows Omar Ameen, who had been living in California as a refugee and was arrested Wednesday on a warrant alleging he killed an Iraqi policeman while fighting for the Islamic State.