Charles F.C. Ruff, the last Watergate special prosecutor and later a highly successful defender of political figures in trouble, most recently as the chief legal adviser to President Clinton during the sex scandal that led to his impeachment trial, died Nov. 19 at D.C. General Hospital after a heart attack. He was 61 and lived in Washington.

Mr. Ruff was D.C. corporation counsel, the city's top lawyer, when he was invited to join the White House in February 1997 while the administration was embroiled in several legal proceedings. Among them was the Whitewater land deal that involved the president and first lady and that the independent counsel's office used to investigate the president's affair with former White House intern Monica S. Lewinsky.

Mr. Ruff, the administration's fifth White House counsel, became known to the millions transfixed by the televised proceedings as the heavyset lawyer who used a wheelchair and whose even-tempered defense of the president lent somelegal solemnity to the heady drama of impeachment.

He had used a wheelchair since 1964, when on a Ford Foundation grant to teach law in Africa he was struck with a still-unknown affliction. As notoriously tight-lipped about his law strategies as his use of the chair, he once told The Washington Post: "Law is a sedentary profession. It's not something I talk about."

Much of his defense of the president hinged on broad assertions of executive privilege and attorney-client privilege that he hoped would prevent testimony in the Lewinsky matter. "The stubborn facts will not budge, nor will the stubborn denials by every participant in their mythical plot," Mr. Ruff said in closing arguments to the Senate.

"You all must cast an eye to the past, looking over our shoulders to be sure that we've learned the right lessons from those who have sat in this chamber before us," he added. "We also must look to the future to be sure that we leave the right lessons to those who come after us."

The House impeached Clinton in December 1998 on charges that the president had lied under oath when questioned about the affair and obstructed justice, and the Senate acquited Clinton in February 1999.

Within the White House, Mr. Ruff was not seen as an obvious team player. He refrained from freely dispensing information to those who did not absolutely need to know the president's legal strategy. "It drives them crazy, and sometimes it drives me crazy to have my colleagues who have other goals in life say, 'Come on,' " he told The Post in 1998.

Mr. Ruff left the White House in the summer of 1999 and returned to Covington & Burling, the law firm he had been associated with since 1982. At his death, he was a senior partner.

"All of us at the White House admired Chuck for the power of his advocacy, the wisdom of his judgment and the strength of his leadership," Clinton said in a statement on hearing of Mr. Ruff's death. "We loved him for his generous spirit and his keen wit, which he used to find humor in even the most challenging circumstances."

Charles Frederick Carson Ruff, a Cleveland native, was a graduate of Swarthmore College and a 1963 graduate of Columbia University law school, where he was 12th in his class of 235.

He was a research associate at Columbia's African Law Center and taught at the University of Pennsylvania before joining the Justice Department as a trial lawyer in 1967. While head of the labor-management section of Justice's criminal division in the early 1970s, he was the chief prosecutor of former United Mine Workers president W.A. "Tony" Boyle on charges of making illegal campaign contributions with union money. Boyle was convicted.

From 1973 to 1977, he was a member of the Watergate special prosecutions office, an independent investigative operation of the Justice Department. Mr. Ruff, who spent the first two years as an assistant special prosecutor, became the fourth--and final--top prosecutor, following Archibald Cox, Leon Jaworski and Henry S. Ruth.

Mr. Ruff had only a handful of assistants, and his duties focused on shutting down the special prosecutor's office, although he had the power to look into new leads.

One such fresh effort included Mr. Ruff's three-month investigation of President Gerald R. Ford's alleged acceptance of illegal campaign contributions during his congressional career. Though the president was cleared, the investigation was viewed in some Republican circles as a way of tainting the party during the 1976 presidential race.

Mr. Ruff was perceived by others as a low-key straight shooter who went out of his way to appear impartial. He returned part of the office's $2 million budget and said he would not write a book about his experiences; Jaworski's "The Right and the Power," by contrast, included materials that Mr. Ruff said he considered confidential.

When he relinquished his duties, Mr. Ruff said he would not support a permanent special prosecutor because such an office was too susceptible to accusations of politically inspired investigations. "We were a tempting repository for that kind of problem," he said, referring to his review of Ford's finances.

The Watergate experience left Mr. Ruff drained and transformed. "You work so damned hard at detaching yourself from emotional reactions, you can't do anything but come away almost artificially detached from the real world," he told The Post at the time.

Mr. Ruff was named deputy inspector general of the Health, Education and Welfare Department in 1978, a job created to look into Medicare and Medicaid fraud. The next year, he became acting deputy attorney general at Justice and helped prosecute members of Congress involved in the Abscam bribery case.

President Jimmy Carter nominated Mr. Ruff for the job of U.S. attorney for the District of Columbia in 1979, a decision that prompted criticism by some local leaders in the majority-black city.

The job, which he held until the dawn of the President Ronald Reagan's administration in 1981, required the prosecution of federal crimes as well as local criminal cases. Mr. Ruff had been an important player in the effort to give the District jurisdiction over local prosecutions, and a Post editorial called him "exceptionally qualified" for the position.

As U.S. attorney, he had minor legal roles in cases involving John W. Hinckley Jr.'s assassination attempt on Reagan and the assassination of Chilean Ambassador Orlando Letelier.

He joined Covington & Burling in 1982 and took on many high-profile clients whose reputations were left legally intact despite the accusations against them. Among those he defended were Sen. John H. Glenn Jr. (D-Ohio) before the Senate Ethics Committee during the investigation of the "Keating Five" savings and loan scandal. Glenn, advised by Mr. Ruff to act reserved during the proceedings, was admonished for "poor judgment" in having received campaign funds from savings and loan operator Charles H. Keating Jr.

Mr. Ruff also was called on to help defend Sen. Charles S. Robb (D-Va.) in a federal probe into Robb's office's possession of a illegally recorded tape of a rival, then-Virginia Lt. Gov. L. Douglas Wilder (D). In what legal observers called a masterful and successful strategy, Mr. Ruff persuaded Robb to appear a second time before a grand jury and then introduced a Justice Department official to instruct the jury that it was not legally bound to follow prosecutors' recommendations for an indictment.

In August 1995, he became the D.C. corporation counsel and oversaw more than 200 lawyers. When he left to join the White House, he was known for having resuscitated the reputation of an office previously beset with missed deadlines, among other problems.

During his career, he also contributed to cases involving the Exxon Valdez oil spill and Clarence Thomas' nomination to the Supreme Court. In the latter case, Mr. Ruff arranged for Anita Hill to take a lie detector test in his office to support her allegations of sexual harassment against Thomas.

In 1993, he was considered strongly by the Clinton administration for the position of deputy attorney general, but that was scuttled when news arose over Mr. Ruff's failure to pay Social Security taxes for a woman who cleaned his home. Mr. Ruff said he believed that he was not liable for those taxes because the woman was 71 and past retirement age.

He held several teaching appointments during his career, often overlapping with his other positions. During the Watergate investigation, he was associate professor at Georgetown University law school.

Survivors include his wife of 38 years, Susan Willis Ruff of Washington; two daughters, Carin Ruff of Shaker Heights, Ohio, and Christina Wagner of Ann Arbor, Mich.; his mother, Margaret Carson of New York; and two grandchildren.