Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

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.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

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.

Idaho Department of Correction spokesman Jeff Ray confirmed Friday that the FBI met with department director Brent Reinke on Thursday to inform him about the investigation. Idaho State Police spokeswoman Teresa Baker said her agency was no longer involved with the investigation and the FBI has taken it over entirely.

U.S. Attorney Wendy Olson in Boise also declined to comment on the scope of the FBI investigation, but did say the agency was looking into fraud.

CCA spokesman Steve Owen said his company would cooperate with investigators.

"Our own internal investigation concluded that this was not a criminal matter, and we remain confident in those findings," Owen said in a prepared statement.

The understaffing has been the subject of federal lawsuits and a contempt of court action against CCA.

— The Associated Press