Canadian authorities said Thursday that suspected Ottawa gunman Michael Joseph Zehaf-Bibeau acted alone, but they are still trying to figure out his motive.
His mother described Zehaf-Bibeau, a recent convert to Islam with a history of drug problems, as being lost and someone "did not fit in."
Why did he kill a Canadian soldier and then storm the Parliament building?
Do the Ottawa shootings raise the risk of ISIS-inspired terrorist attacks within the United States?
CBS News Homeland Security correspondent Bob Orr and senior security contributor Michael Morell weigh in.