When the FBI raided a business connected to Rep. Rick Renzi, R-Ariz., last week, the lawmaker joined a group that has sadly grown less exclusive in recent years: House intelligence committee members confirmed to be facing a federal criminal investigation. Since 2005, four sitting members of the House panel entrusted with the nation’s deepest secrets have come under FBI scrutiny. The committee, known formally as the House Permanent Select Committee on Intelligence (HPSCI, for short), reviews classified budgets and operational plans for the CIA, the NSA and other so-called three-letter agencies. Unlike nearly everyone else who works with the nation’s deepest national security secrets, lawmakers on intelligence committees undergo no background checks, no polygraphs and no lifestyle audits. They are automatically waived in to review everything from secret satellite data to nuclear weapons intelligence. "That means the people who serve on that committee have to have the highest integrity possible," said Vince Cannistraro, a former senior CIA official and case officer. Click Here for Full Blotter Coverage. Following the FBI’s raid last week on the offices of an insurance company owned by his wife, Renzi stepped down from the intelligence panel. Whether or not the FBI finds any evidence of wrongdoing, experts say the recent probes are troubling. "Name the one committee you don’t want any corruption on," said Keith Ashdown of Taxpayers for Common Sense, a Washington, D.C.-based group which watchdogs congressional spending. "There’s a special obligation that comes with [serving on] that committee," Cannistraro concurred. At least two investigations into HPSCI members have involved allegations of bribes-for-contracts schemes between lawmakers and intelligence contractors. Former California GOP Rep. Randy "Duke" Cunningham is in jail for taking millions in bribes in exchange for funneling government contracts. Newly-elected Nevada governor and former Rep. Jim Gibbons, R-Nev., currently faces an investigation into whether he improperly helped a friend’s contracting firm get business, payments and favored treatment from national security agencies and officials. Through his lawyer, Gibbons has said he is confident "that all of this is going to be favorably resolved." In Arizona, Renzi is suspected of taking a $200,000 payment from his business partner for using the power of his office to force the purchase of his business partner’s land at an unreasonable price. Renzi has denied the charges and said the FBI raid on his wife’s insurance business as "the first step toward getting the truth out." In 2005, the FBI reportedly opened an investigation into whether Rep. Jane Harman, D-Calif., then the senior Democrat on the committee, cut an improper deal with a powerful pro-Israel lobbying group in exchange for supporting her bid to head the committee. Harman has denied wrongdoing, and the probe has reportedly stalled since failing to find evidence of wrongdoing. Cannistraro, who once served as a clandestine CIA case officer in the Middle East and elsewhere, said it’s painful for those who make careers out of learning and keeping the nation’s secrets to hear stories of the corruption, both proven and alleged, that have recently dogged the very lawmakers to whom they entrust their secrets. "They get disturbed by it," the 27-year CIA veteran told ABC News. "They’re not in a position to tell the committee they can’t have [certain] intelligence. It’s theirs by statute."