In this Feb. 11, 2016 photo, Shaun McCarthy, of Avoca, Iowa, poses for a photo in Omaha, Neb. A boarding school for troubled teenagers in Iowa that is being investigated by the FBI routinely kept pupils in small concrete &quot;isolation boxes&quot; for days or weeks and wouldn't let them out unless they sat in a specific posture for 24 hours, according to several former students including McCarthy. (AP Photo/Nati Harnik) Photo: Nati Harnik