BOISE, Idaho (AP) — The FBI has launched an investigation of the Corrections Corporation of America over the company's running of an Idaho prison with a reputation so violent that inmates dubbed it "Gladiator School." The Nashville, Tenn.-based CCA has operated Idaho's largest prison for more than a decade, but last year, CCA officials acknowledged it had understaffed the Idaho Correctional Center by thousands of hours in violation of the state contract. CCA also said employees falsified reports to cover up the vacancies. The announcement came after an Associated Press investigation showed CCA sometimes listed guards as working 48 hours straight to meet minimum staffing requirements. The Idaho State Police was asked to investigate the company last year but didn't, until amid increasing political pressure, the governor ordered the agency to do so last month. Democratic state lawmakers asked the FBI to take up the case last month. CCA spokesman Steve Owen says his company would cooperate with investigators. The understaffing has been the subject of federal lawsuits and a contempt of court action against CCA. The ACLU sued on behalf of inmates at the Idaho Correctional Center in 2010, saying understaffing contributed to the high levels of violence there.