The director of the Federal Bureau of Prisons, Harley Lappin, told a legislative panel that a new perimeter fence and other measures would make Thomson Correctional Center "the most secure of all federal prisons in the country."
Meanwhile, as the New York Times reports, lawmakers have rebuffed administration overtures to fund the transfer of prisoners - likely pushing the closure of the prison facility at Guantanamo Bay back to at least 2011, a year later than President Obama promised when he took office.
Officials told the Times they need to up to 10 months to make security upgrades at the little-used facility before it will be usable as a maximum-security federal prison. That can't begin until the government purchases the facility - and Democratic lawmakers refused to include funding to do so in the 2010 military spending bill.
The next best opportunity to secure the funding appears to be in a supplemental appropriations bill that won't be finished for months.
The 12-member Commission on Government Forecasting and Accountability, which hosted the hearing Tuesday, could vote on a recommendation to sell the prison, which skirts the Mississippi River. But Gov. Pat Quinn, who was traveling and did not attend the meeting, does not have to follow the recommendation.
The hearing adjourned Tuesday night, and the commission said it would not vote on the proposal before Jan. 14.
Many in Thomson, about 20 miles from Sterling, and other northwest Illinois communities say they welcome the estimated 3,000 jobs that the White House says would be generated by the prison. But opponents say the move is too risky.
"Terrorists would want to hit us to make a point, here in the Midwest, in the American heartland," protester Amanda Norms said before the meeting. "Is a little economic gain worth the risk?"
Jay Alan Liotta, the Defense Department's principal director in the office of detainee policy, insisted the area would be safe.
"Allow me to be perfectly clear: The security of the facility and that of the surrounding community is our paramount concern," he told the panel.
Earlier in the day, members of the media got a glimpse of the prison. Many of its interior common areas, including library and classroom space, are still gleaming eight years after the facility's construction. The outside is more forbidding, with barbed wire atop fences and guard towers.
The state built the prison at a cost of $145 million in 2001 in Thomson, a town of some 450 people about 150 miles west of Chicago. But budget problems prevented it from ever fully opening. It has 1,600 cells, but currently houses only about 200 minimum-security inmates, according to state officials.
More than 300 people crowded into a high school auditorium in Sterling for Tuesday's hearing.
Opponents groaned and hissed when Quinn's chief operating officer, Jack Levin, said his boss "would never do anything that puts people at risk." He also told the panel that the Thomson facility would be "the most secure federal prison in the nation."
When he finished his two-minute statement someone yelled, "That's a lie."
The uproar prompted a reprimand from the panel's chairman, state Sen. Jeffrey Schoenberg.
"This is going to be a long hearing," Schoenberg said, sounding his gavel after one chorus of boos. "It will be even longer without the necessary decorum."
Critics have complained that they were not able to comment to the panel before Quinn, with White House backing, decided earlier this month to sell Thomson to the federal government.
"We woke up one morning and were told that Gitmo was moving to Illinois," said Denise Cattoni of the Illinois Tea Party organization.
Cattoni said that with detainees in the state, she feared Illinois would become "a focus of revenge" for extremists.
But leaders from communities near Thomson told the panel their constituents are clamoring for the kind of economic boost a fully open Thomson prison would provide.
"I hear a lot of fear, but there's another kind of fear - the fear of losing your job or your home," said Bonnie Heckman Foust, village president of nearby Shannon.
Several construction unions also spoke in favor of the Thomson sale. One state prison union said it opposes a federal takeover, though, saying Thomson should be used instead to relieve rampant overcrowding at state prisons across Illinois.
President Obama ordered the federal Bureau of Prisons to buy the prison. The decision is an important step toward closing Guantanamo Bay, which has long been a global symbol of the Bush administration's approach to national security.
But its takeover of Thomson won't solve all the administration's Guantanamo-related problems. More than 200 detainees will remain there, and the White House faces other legal issues and potential resistance from Congress.