BOISE, Idaho (AP) — A former warden for private prison giant Corrections Corporation of America says he didn't know that mandatory posts at the Idaho prison he led were chronically unstaffed.

Tim Wengler, the former warden at the CCA-run Idaho Correctional Center south of Boise, told U.S. District Judge David Carter on Wednesday that in his three years on the job, he never noticed that some mandatory security posts went unstaffed or that some staffing reports were falsified to cover up the missing staff hours.

Wengler was one of several CCA officials and employees to testify during a contempt-of-court hearing over whether the Nashville, Tenn.-based company is abiding by the terms of a settlement it reached with Idaho inmates two years ago.

The inmates, represented by the American Civil Liberties Union of Idaho, sued in 2010, contending that the prison was so violent that prisoners call it "Gladiator School." CCA denied the allegations but reached a deal in 2011 requiring widespread operating changes including increased staffing. Earlier this year, however, the company acknowledged that it understaffed the mandatory minimum posts at the prison by 4,800 hours during seven months in 2012. Shortly after that admission, CCA announced that the 46-year-old Wengler was retiring after 17 years with the company.

But in his testimony Wednesday, Wengler said he was still under contract with CCA and still getting paid by the company. His job is "to assist them with things they need," Wengler said, including making sure the company is following through with the settlement it reached with the Idaho inmates. Wengler said he couldn't remember if his employment contact prohibits him from disparaging or testifying against CCA.

Wengler also said he never suspected that the mandatory security staff positions required under both CCA's $29 million contract with the Idaho Department of Correction and the court settlement order were frequently left unstaffed for all or part of the shift.

"I believed we were fulfilling the terms of the settlement," Wengler said.

He laid the blame at the feet of his subordinates, saying it was apparent "that somebody knew something" and was falsifying documents, but that he never spotted any inaccuracies when he looked at the staffing rosters.

Carter frequently interjected his own sharp questions and comments during question, asking another CCA official how much money the company should pay back Idaho taxpayers for failing to meeting the contract terms. The judge said the 4,800 hours of understaffing appeared to be a low estimate of how much time went unfilled.

Scott Craddock, CCA's top ethics officer, said those hours only accounted for understaffing that occurred during the night shift during a seven-month span, and that CCA didn't fully investigate the number of hours that were understaffed during the day shift.

A partial review showed at least 152 hours unstaffed in May and another 300 in June, Craddock said.

"As I understand it, CCA has represented they're going to pay back IDOC. What amount should they pay them?" the judge asked Craddock.

"Let's add together," he said, "4800 hours, plus 152, plus 300, what is that? ... And we don't know what the day shift for gosh, July, August, September, October, November, we don't know that, do we? So 4800 hours is kind of a pretty low number, isn't it?"

"We reported what we did a detailed report on," Craddock said, saying they based the estimate on the period they investigated, which was the night shift for seven months.

ACLU attorney Stephen Pevar said he would show evidence that CCA violated the court's order by failing to fill thousands of hours of security posts, that the company tried to cover up the understaffing by filing false documents with the state, that CCA deliberately avoided learning who was responsible for the problems, and that despite learning of the staffing problems more than a year ago, the understaffing continues to this day.

Pevar said the understaffing problems occurred because there was "inadequate supervision by the warden. Someone was asleep at the wheel."

CCA's attorney Daniel Struck said hiring and retaining qualified correctional officers is a problem at prisons of all sorts, nationwide.

CCA's management team at the Idaho Correctional Center did what it could to try to keep the mandatory posts filled, Struck said, and even hired more staffers than were required under the contract to meet the terms of the court settlement.

"The evidence shows there's always going to be challenges in filling mandatory posts," Struck said. He said the company implemented a plan to make sure the vacancies don't happen again, and that there were no increases in inmate assaults as a result of the understaffing.

"As a result there is no reason to punish CCA for taking the actions that they did," Struck said.

Kevin Myers, a regional managing director of operations for CCA, testified the company offered to pay the Idaho Department of Correction $117,000 to cover the understaffed hours. That amounts to about $24.37 an hour.

Myers didn't say what IDOC's response was. The company is paid $29 million a year by Idaho under its state contract.

IDOC spokesman Jeff Ray says the department declined the offer because officials are waiting for the results of an Idaho state police investigation into the understaffing.