No sooner did Alberto Gonzales resign as attorney general last month than he retained a high-powered Washington criminal-defense lawyer to represent him in continuing inquiries by Congress and the Justice Department.

Gonzales's choice of counsel, George Terwilliger—a partner at White & Case—is ironic if not surprising. A former deputy attorney general under the first President Bush, who later helped oversee GOP lawyers in the epic Florida recount battle of 2000, Terwilliger had been a White House finalist to replace Gonzales—only to be aced out at the last minute by retired federal judge Michael Mukasey.

The top concern for Gonzales, and now Terwilliger, is the expanding investigation by Glenn Fine, the Justice Department's fiercely independent inspector general, according to three legal sources familiar with the matter who declined to speak publicly about ongoing investigations. Originally, Fine's internal Justice probe—conducted in conjunction with lawyers from the department's Office of Professional Responsibility—focused on the mass dismissal of U.S. attorneys late last year. The investigation has since broadened to include, among other matters, charges that Gonzales lied to Congress about the Bush administration's warrantless surveillance program and the circumstances surrounding his late-night March 10, 2004, visit to the hospital room of then attorney general John Ashcroft. At the same time, Congress is continuing to pursue more documents on harsh CIA interrogation techniques approved by Gonzales.

Fine's investigators, who received high-level security clearances, have been interviewing key players involved in the now-famous bedside confrontation in Ashcroft's hospital room, according to the legal sources. During the visit that evening, Gonzales, then White House counsel, sought to persuade an ailing and heavily medicated Ashcroft to overrule department lawyers who had refused to sign off on classified surveillance activities ordered by President Bush because of concerns about their legality. A rash of senior Justice Department officials—including then deputy attorney general James Comey and FBI Director Robert Mueller—threatened to resign over the incident.

Yet when Gonzales appeared before the Senate Judiciary Committee in February 2006, he testified that "there has not been any serious disagreement" about the president's surveillance program. He did acknowledge disputes about "other intelligence activities" that he declined to identify.

One former administration official close to Gonzales's team (who, like others interviewed for this story, requested anonymity in talking about an ongoing probe) said the former attorney general is concerned that Fine may end up making a criminal referral to the Public Integrity Section of the Justice Department—or even seek the appointment of a special counsel to determine if Gonzales made false statements to Congress.