WASHINGTON — As the investigation into the leak of a CIA agent's name hurtles to a conclusion, special prosecutor Patrick Fitzgerald has zeroed in on the role of Vice President Dick Cheney's office, according to lawyers familiar with the case and government officials. They say the prosecutor has assembled evidence that suggests Cheney's long-running feud with the CIA contributed to the unmasking of operative Valerie Plame.

In grand-jury sessions, including with New York Times reporter Judith Miller, Fitzgerald has pressed witnesses on what Cheney may have known about the effort to push back against former Ambassador Joseph Wilson, a critic of the war in Iraq, including the leak of his wife's position at the CIA, Miller and others said. But Fitzgerald has focused more on the role of Cheney's top aides, including Chief of Staff I. Lewis "Scooter" Libby, lawyers involved in the case said.

One former CIA official told prosecutors that up to two months before Plame was unmasked in July 2003, Cheney's office was trying to obtain information about a trip her husband had made to Niger in 2002 to determine whether Iraq had attempted to acquire uranium there, according to a person familiar with the account.

It is not clear whether Fitzgerald plans to charge Cheney or anyone else in the Bush administration with a crime, but administration officials are braced for possible indictments as early as this week.

Lawyers in the case said Fitzgerald has focused extensively on whether behind-the-scenes efforts by the vice president's office and senior aides to President Bush were part of a criminal campaign to punish Wilson, in part, by unmasking his wife.

On July 6, 2003, Wilson contended in an opinion piece in The New York Times that the administration had twisted intelligence to justify invading Iraq on March 20, 2003.

Eight days later, on July 14, Plame's name and her CIA employment appeared in a syndicated column by Robert Novak.

Charges could range from a broad conspiracy case to more narrowly drawn indictments for obstruction of justice or perjury, according to lawyers involved in the case. Charges are considered less likely on the law that initially triggered Fitzgerald's probe, which makes it illegal to deliberately unmask an undercover intelligence agent, because of the difficulty in meeting that statute's exacting standards for prosecution.

Lea Anne McBride, a Cheney spokeswoman, declined to comment yesterday on whether the vice president had been contacted by Fitzgerald about his status in the case, except to say: "This is an ongoing investigation, and we are fully cooperating."

But with the case reaching a climax, it is increasingly clear that Cheney and his aides have been deeply enmeshed in events surrounding the Plame case from the outset.

It was a request by Cheney for more information from the CIA that, unknown to him, started a chain of events that led to Wilson's trip to Niger in 2002. His staff pressed the CIA for information about the trip one year later. And it was Libby who talked about Wilson's wife with at least two reporters before her identity became public.

Fitzgerald's spokesman told The Associated Press yesterday that the prosecutor planned to announce his conclusions in Washington, where the grand jury has been meeting, instead of Chicago, where the prosecutor is based. Some lawyers close to the case said Fitzgerald could announce his findings as early as tomorrow.

In the course of the investigation, Fitzgerald has been exposed to the intense, behind-the-scenes fight between Cheney's office and the CIA over prewar intelligence and the vice president's central role in compiling and then defending the intelligence used to justify the war.

Miller, in a first-person account Sunday in the Times, recalled that Libby complained in a June 23, 2003, meeting in his office that the CIA was engaged in "selective leaking" and in a "hedging strategy" that would make the agency look equally prescient whether or not weapons of mass destruction were found in Iraq.

The special prosecutor has interviewed a number of Cheney aides including Mary Matalin, his former strategist; Catherine Martin, his former communications adviser; and Jennifer Millerwise, his former spokeswoman.

Miller, who now has testified twice before the grand jury after spending 85 days in jail for refusing to cooperate with Fitzgerald, wrote that the prosecutor asked her whether Cheney "had known what his chief aide [Libby] was doing and saying" about Wilson.

Building the case

Starting in the days after the Sept. 11, 2001, terrorist attacks, the vice president was at the forefront of a White House campaign to convince Congress and the American public that invading Iraq was central to defeating terrorists worldwide. Cheney, a longtime proponent of toppling Saddam Hussein, led the White House effort to build the case that Iraq was an imminent threat because it possessed a dangerous arsenal of weapons.

Before the war, he went to CIA headquarters for briefings, an unusual move that some critics interpreted as an effort to pressure intelligence officials into supporting his view of the evidence. After the war, when critics started questioning whether the White House relied on faulty information to justify the war, Cheney and Libby were central to the effort to defend the intelligence and discredit the naysayers in Congress and elsewhere.

Administration officials acknowledge that Cheney was immersed in Iraq intelligence, and pressed aides repeatedly for information on weapons programs. He regularly requested follow-up information from the CIA and others when a piece of intelligence caught his eye.

Wilson's trip, for example, was triggered by a question Cheney asked during a regular morning intelligence briefing. He had received a Defense Intelligence Agency report alleging Iraq had sought uranium from Niger and wanted to know what else the CIA might have known. Cheney's office was not told ahead of time about Wilson's mission to investigate the claim.

Wilson concluded the allegations that Iraq was seeking uranium in Niger were unfounded. But the Bush administration decided to make the allegations a central piece of its contention that Saddam had designs on weapons of mass destruction. Administration officials rebuffed concerns from some in the CIA and included the allegations in Bush's January 2003 State of the Union address.

Wilson set out to discredit the claim, at first working through back channels and then, on July 6, 2003, in the Times' op-ed piece in which he stated that the administration "twisted" intelligence to exaggerate the Iraqi threat.

Murky information

One fact apparently critical to Fitzgerald's inquiry is when Libby learned about Plame and her CIA employment. Information that has emerged so far leaves this issue murky.

A former CIA official told investigators that Cheney's office was seeking information about Wilson in May 2003, but it's not certain that officials with the vice president learned of the Plame connection then.

Miller, in her account, said Libby raised the Plame issue in the June 23, 2003, meeting, describing her as a CIA employee and asserting she had arranged Wilson's trip to Niger. Earlier that month, Libby discussed Wilson's trip with The Washington Post but never mentioned Wilson's wife.

Material from Bloomberg News is included in this report