Security Forces found Mass Grave in Badush Prison, near Mosul

They did not disclose how they determined that number but it is consistent with a Human Rights Watch report of Daesh killings at the prison.

They reported in mid-2014 that Daesh attacked Badush prison and killed more than 670 Shia prisoners and that they also held hundreds of kidnapped women from Iraq’s Yazidi minority there.

According to survivors, Daesh shot the Shia prisoners after separated them from other sects with rifles and machine guns and also killed a number of Kurdish and Yazidi prisoners.