The last several years have brought a parade of dark revelations about the George W. Bush administration, from the manipulation of intelligence to torture to extrajudicial spying inside the United States. But there are growing indications that these known abuses of power may only be the tip of the iceberg. Now, in the twilight of the Bush presidency, a movement is stirring in Washington for a sweeping new inquiry into White House malfeasance that would be modeled after the famous Church Committee congressional investigation of the 1970s.

While reporting on domestic surveillance under Bush, Salon obtained a detailed memo proposing such an inquiry, and spoke with several sources involved in recent discussions around it on Capitol Hill. The memo was written by a former senior member of the original Church Committee; the discussions have included aides to top House Democrats, including Speaker Nancy Pelosi and Judiciary Committee chairman John Conyers, and until now have not been disclosed publicly.

Salon has also uncovered further indications of far-reaching and possibly illegal surveillance conducted by the National Security Agency inside the United States under President Bush. That includes the alleged use of a top-secret, sophisticated database system for monitoring people considered to be a threat to national security. It also includes signs of the NSA’s working closely with other U.S. government agencies to track financial transactions domestically as well as globally.

The proposal for a Church Committee-style investigation emerged from talks between civil liberties advocates and aides to Democratic leaders in Congress, according to sources involved. (Pelosi’s and Conyers’ offices both declined to comment.) Looking forward to 2009, when both Congress and the White House may well be controlled by Democrats, the idea is to have Congress appoint an investigative body to discover the full extent of what the Bush White House did in the war on terror to undermine the Constitution and U.S. and international laws. The goal would be to implement government reforms aimed at preventing future abuses — and perhaps to bring accountability for wrongdoing by Bush officials.

“If we know this much about torture, rendition, secret prisons and warrantless wiretapping despite the administration’s attempts to stonewall, then imagine what we don’t know,” says a senior Democratic congressional aide who is familiar with the proposal and has been involved in several high-profile congressional investigations.

“You have to go back to the McCarthy era to find this level of abuse,” says Barry Steinhardt, the director of the Program on Technology and Liberty for the American Civil Liberties Union. “Because the Bush administration has been so opaque, we don’t know [the extent of] what laws have been violated.”

The parameters for an investigation were outlined in a seven-page memo, written after the former member of the Church Committee met for discussions with the ACLU, the Center for Democracy and Technology, Common Cause and other watchdog groups. Key issues to investigate, those involved say, would include the National Security Agency’s domestic surveillance activities; the Central Intelligence Agency’s use of extraordinary rendition and torture against terrorist suspects; and the U.S. government’s extensive use of military assets — including satellites, Pentagon intelligence agencies and U2 surveillance planes — for a vast spying apparatus that could be used against the American people.

Specifically, the ACLU and other groups want to know how the NSA’s use of databases and data mining may have meshed with other domestic intelligence activities, such as the U.S. government’s extensive use of no-fly lists and the Treasury Department’s list of “specially designated global terrorists” to identify potential suspects. As of mid-July, says Steinhardt, the no-fly list includes more than 1 million records corresponding to more than 400,000 names. If those people really represent terrorist threats, he says, “our cities would be ablaze.” A deeper investigation into intelligence abuses should focus on how these lists feed on each other, Steinhardt says, as well as the government’s “inexorable trend towards treating everyone as a suspect.”

“It’s not just the ‘Terrorist Surveillance Program,'” agrees Gregory T. Nojeim from the Center for Democracy and Technology, referring to the Bush administration’s misleading name for the NSA’s warrantless wiretapping program. “We need a broad investigation on the way all the moving parts fit together. It seems like we’re always looking at little chunks and missing the big picture.”

A prime area of inquiry for a sweeping new investigation would be the Bush administration’s alleged use of a top-secret database to guide its domestic surveillance. Dating back to the 1980s and known to government insiders as “Main Core,” the database reportedly collects and stores — without warrants or court orders — the names and detailed data of Americans considered to be threats to national security.

According to several former U.S. government officials with extensive knowledge of intelligence operations, Main Core in its current incarnation apparently contains a vast amount of personal data on Americans, including NSA intercepts of bank and credit card transactions and the results of surveillance efforts by the FBI, the CIA and other agencies. One former intelligence official described Main Core as “an emergency internal security database system” designed for use by the military in the event of a national catastrophe, a suspension of the Constitution or the imposition of martial law. Its name, he says, is derived from the fact that it contains “copies of the ‘main core’ or essence of each item of intelligence information on Americans produced by the FBI and the other agencies of the U.S. intelligence community.”

Some of the former U.S. officials interviewed, although they have no direct knowledge of the issue, said they believe that Main Core may have been used by the NSA to determine who to spy on in the immediate aftermath of 9/11. Moreover, the NSA’s use of the database, they say, may have triggered the now-famous March 2004 confrontation between the White House and the Justice Department that nearly led Attorney General John Ashcroft, FBI director William Mueller and other top Justice officials to resign en masse.

The Justice Department officials who objected to the legal basis for the surveillance program — former Deputy Attorney General James B. Comey and Jack Goldsmith, the former head of the Office of Legal Counsel — testified before Congress last year about the 2004 showdown with the White House. Although they refused to discuss the highly classified details behind their concerns, the New York Times later reported that they were objecting to a program that “involved computer searches through massive electronic databases” containing “records of the phone calls and e-mail messages of millions of Americans.”

According to William Hamilton, a former NSA intelligence officer who left the agency in the 1970s, that description sounded a lot like Main Core, which he first heard about in detail in 1992. Hamilton, who is the president of Inslaw Inc., a computer services firm with many clients in government and the private sector, says there are strong indications that the Bush administration’s domestic surveillance operations use Main Core.

Hamilton’s company Inslaw is widely respected in the law enforcement community for creating a program called the Prosecutors’ Management Information System, or PROMIS. It keeps track of criminal investigations through a powerful search engine that can quickly access all stored data components of a case, from the name of the initial investigators to the telephone numbers of key suspects. PROMIS, also widely used in the insurance industry, can also sort through other databases fast, with results showing up almost instantly. “It operates just like Google,” Hamilton told me in an interview in his Washington office in May.

Since the late 1980s, Inslaw has been involved in a legal dispute over its claim that Justice Department officials in the Reagan administration appropriated the PROMIS software. Hamilton claims that Reagan officials gave PROMIS to the NSA and the CIA, which then adapted the software — and its outstanding ability to search other databases — to manage intelligence operations and track financial transactions. Over the years, Hamilton has employed prominent lawyers to pursue the case, including Elliot Richardson, the former attorney general and secretary of defense who died in 1999, and C. Boyden Gray, the former White House counsel to President George H.W. Bush. The dispute has never been settled. But based on the long-running case, Hamilton says he believes U.S. intelligence uses PROMIS as the primary software for searching the Main Core database.

Hamilton was first told about the connection between PROMIS and Main Core in the spring of 1992 by a U.S. intelligence official, and again in 1995 by a former NSA official. In July 2001, Hamilton says, he discussed his case with retired Adm. Dan Murphy, a former military advisor to Elliot Richardson who later served under President George H.W. Bush as deputy director of the CIA. Murphy, who died shortly after his meeting with Hamilton, did not specifically mention Main Core. But he informed Hamilton that the NSA’s use of PROMIS involved something “so seriously wrong that money alone cannot cure the problem,” Hamilton told me. He added, “I believe in retrospect that Murphy was alluding to Main Core.” Hamilton also provided copies of letters that Richardson and Gray sent to U.S. intelligence officials and the Justice Department on Inslaw’s behalf alleging that the NSA and the CIA had appropriated PROMIS for intelligence use.

Hamilton says James B. Comey’s congressional testimony in May 2007, in which he described a hospitalized John Ashcroft’s dramatic standoff with senior Bush officials Alberto Gonzales and Andrew Card, was another illuminating moment. “It was then that we [at Inslaw] started hearing again about the Main Core derivative of PROMIS for spying on Americans,” he told me.

Through a former senior Justice Department official with more than 25 years of government experience, Salon has learned of a high-level former national security official who reportedly has firsthand knowledge of the U.S. government’s use of Main Core. The official worked as a senior intelligence analyst for a large domestic law enforcement agency inside the Bush White House. He would not agree to an interview. But according to the former Justice Department official, the former intelligence analyst told her that while stationed at the White House after the 9/11 attacks, one day he accidentally walked into a restricted room and came across a computer system that was logged on to what he recognized to be the Main Core database. When she mentioned the specific name of the top-secret system during their conversation, she recalled, “he turned white as a sheet.”

An article in Radar magazine in May, citing three unnamed former government officials, reported that “8 million Americans are now listed in Main Core as potentially suspect” and, in the event of a national emergency, “could be subject to everything from heightened surveillance and tracking to direct questioning and even detention.”

The alleged use of Main Core by the Bush administration for surveillance, if confirmed to be true, would indicate a much deeper level of secretive government intrusion into Americans’ lives than has been previously known. With respect to civil liberties, says the ACLU’s Steinhardt, it would be “pretty frightening stuff.”

The Inslaw case also points to what may be an extensive role played by the NSA in financial spying inside the United States. According to reports over the years in the U.S. and foreign press, Inslaw’s PROMIS software was embedded surreptitiously in systems sold to foreign and global banks as a way to give the NSA secret “backdoor” access to the electronic flow of money around the world.