Nigeria President Vows War Crimes Probe

WARNING, GRAPHIC CONTENT | VIDEO: Nigerian President Muhammadu Buhari Tweeted that his government will leave "no stone unturned" investigating charges of widespread torture, abuse and killing of more than 8,000 prisoners during the military’s offensive against the terror group Boko Haram, according to a recent repory by Amnesty International. Henry Ridgwell reports from London.