Joseph R. Caldwell, a partner in a Washington law firm that specializes in white-collar criminal cases, will be chief of staff and part of a triumvirate of top advisers in the administration of D.C. Mayor-Elect Sharon Pratt Dixon, according to aides to Dixon.

Caldwell will join David Byrd, the new general assistant, and a city administrator who has yet to be announced as the three top advisers to Dixon in shaping and implementing new policy for the District, aides say.

Neither Byrd nor Caldwell has extensive administrative experience or intimate knowledge of D.C. government. Byrd, 30, a political novice who once worked in the entertainment industry, managed Dixon's overwhelming and surprisingly successful campaign.

Caldwell, 41, is a partner at Miller Cassidy Larroca & Lewin, a relatively small, well-respected law firm that has represented many prominent political figures including former president Richard M. Nixon, former White House aide Michael S. Deaver and Attorney General Edwin Meese III. He served as informal counsel to Dixon during the campaign and is co-chairman of her public safety transition committee.

The relationship and chemistry he developed with the mayor-elect in those two endeavors were primary considerations in choosing him for the post, sources say.

Dixon will start each work day meeting with Byrd, Caldwell and the city administrator.

President Ronald Reagan used the triumvirate structure to "prop him up," said Michael J. Frazier, a legislative assistant to Sen. Edward M. Kennedy (D-Mass.) and former aide to Mayor Marion Barry who is co-chairman of the Dixon transition committee that has studied ways to restructure the mayor's personal staff. Dixon chose the configuration because "she wants a number of ideas around her," he said. "She doesn't want everything to be funneled through one person."

Caldwell, a native of Jackson, Miss., graduated from Syracuse University in 1971. He received a law degree from Rutgers University in 1974 and a master's in law from Georgetown University in 1984. The following year, he received a master's in public administration from Harvard University.

He is a former deputy attorney general for criminal justice in New Jersey, counsel to the Supreme Court and assistant to Chief Justice Warren E. Burger.

The chief of staff traditionally has supervised employees within the mayor's office, but the role may be altered as Dixon's staff takes shape.

A top Dixon aide said that Caldwell will be paid about $80,000 a significant drop from the $100,000 he estimated Caldwell makes as a lawyer.

The mayor-elect aims to reduce spending on the Office of the Mayor by 10 percent, the aide said. As a result, many people who choose to take posts with the city will have to take pay cuts from the private sector.

Byrd, who was raised in Springfield, Mass., came to the District in 1978 to study English at Howard University. He met Dixon at the school, where she served as a trustee. He completed three years of study there in spurts that he financed with jobs at Piedmont Airlines, where he did customer service, and at the Library of Congress where he was a researcher.

He has also worked in employee relations at the Los Angeles Times and as a producer for a Canadian band. Just before joining the Dixon campaign earlier in the year, Byrd was an intern at the Democratic National Committee.

Dixon has described Byrd as her alter-ego.

"David is the person I like to run ideas by because we play off of each other well," she said during the campaign. "I think I have a pretty good instinct about who has raw talent. He has a good, creative mind, he stays on point and he gives me good feedback in a way that is constructive and useful."

"David is going to be the closest adviser to the mayor," Frazier said. "I think David is the one who will set the overall agenda for the office. I think she {Dixon} clearly has implicit faith in David and she ought to -- he ran a good campaign."

Byrd's role will be closest to the one Deaver played in Reagan's triumvirate, "making him look his best to the American public," Frazier said. "I think David's concern is that Sharon keeps her campaign promises, what her long-term commitments are to the city and how she looks on the daily news."

Mildred Goodman, who was Dixon's deputy campaign manager, is slated to be secretary of the District of Columbia, a top aide said. Goodman, a member of the D.C. Democratic State Committee, ran Michael S. Dukakis's 1988 presidential campaign in D.C. She retired from the federal Department of Transportation as deputy director for civil rights and has served as national president of Blacks in Government.

The secretary post handles a range of administrative and clerical responsibilities for the District government.

Dixon and her transition search committee interviewed four finalists for the job of city administrator over the weekend.

The leading candidate will be offered the job if he passes a background check that is being conducted, sources say. Dixon is scheduled to name the city administrator by the end of the week.

Among those who were considered for city administrator and apparently rejected were Sylvester Murray, 49, a former city manager of Cincinnati and San Diego; and Gerald Seals, 37, who is city manager of Corvallis, Ore.

Staff writer Saundra Torry contributed to this report.