Millionaire developer Dominic F. Antonelli Jr. and former city official Joseph P. Yeldell looked across a U.S. courtroom here yesterday at an all black, largely female jury of middle-class Washingtonians who swore to decide honestly and fairly the fate of the two men in the criminal conspiracy trial.

The makeup of that jury was no accident. It arose from the controlled clash between prosecutors and defense attorneys over which of the 154 prospective jurors would be more likely to favor their side.

The prosecution, for instance, challenged a young woman carrying a motorcycle helmet and a man who moved in the courtroom as if he was boogeying to music that no one else could hear. Both were black and, said lawyers familiar with the jury selection process, might have been thought by prosecution attorneys to admire the way Antonelli, a white, and Yeldell, a black, rose from poverty to achieve success.

The defense, on the other hand, challenged a former newspaper man who now works for The Newspaper Guild. Many of the charges covered by the three indictments were first detailed in The Washington Post two years ago.

"I don't know myself what reasons project lawyers to say they would rather have someone else sit (as a juror) in a particular case," Judge Gerhard A. Gesell explained to the 81 potential jurors who survived the first cuts and now could be challenged by either prosecution or defense for no stated reason.(The prosecution had nine such pre emptive challenges, the two defendants 16.)

"It's just part of the lawyering of the case," continued Gesell.

For lawyers, the selection of a jury is a key element of their case. "Jury selection is crucial to constructing a winning case," said Maureen McLaughlin, a jury consultant from Atlanta who has worked for such diverse clients as dope smugglers and relatives of Howard Hughes in the "Mormon will" trial.

The defense attorneys in the Antonelli-Yeldell case received a list of 450 potential jurors late last week that provided their names, addresses, ages and occupations. According to both prosecutor and defense attorneys here, those are keys to picking the "The defense (in the Antonelli-Yeldell case) tried for people who were black, who had lived in Washington a long time and who were 40 years and older. They want civil servants who understand the government and understand guys like Yeldell," said one attorney who has had peripheral contact with the case.

That is the kind of jury that was selected to try Antonelli and Yeldell. While the ages range from 19 to 75, its average is 41 years old. There are nine women and three men; one is retired, three are government employes. The six alternate jurors fit the same mold: their average age is 42; four work for the government and one is a retired mailman, and there are four women and two men.

All whites who made into the jury box for the final selection were challenged, six by the defense and three by the prosecution.

The defense challenged a white man who had retired a year ago from the FBI. The government cut a white woman whose husband was an official of the American Bankers Association, leading to speculation the prosecuters feared she might be sympathetic to Antonelli who founded and has sat on the board of the Madison National Bank.

The jurors are Lethia Eldrige, 19, cashier for Holly Farms: Pretha Beckhem, 53, maid at Howart Johnson; Percell Veney, 53, tailor at Sears; Elavn Conyers, 24, Treasury Department employe; Lena Glass, 61, domestic; Pamela Berhoud, 25, United Mine Workers Health & Retirement Fund Employe; Alease Spencer, 52, State Department secretary; Brenday Royster, 27, senior data technician; Diane Jones, 27, accountant clerk with Amtrak; John Morgan, 75, retired; Viriene Ingram, 25, employe of People Drugs, and James Pickett, 50, National Institutes of Health employe.

The alternates are Fannie Jackson, 57, government laboratory helper; Carlton Watson, 58, retired letter carrier; Paulette Shelton, 29, medical records supervisor at Childrens Hospital; Pattie Nichols, clerk typist at the Equal Employment Opportunities Commission, and John O'Neal, 41, laborer for the D.C. public schools.

They survived an arduous and sometimes boring selection process that stretched through one full day and the first 80 minutes of the second day of the trial.

The questioning was carried out by Gesell, mostly in private with the attorneys present. He first weeded out the obvious - those who could not be locked away from families and businesses during the three to four weeks the trial is expected to take.

Then he moved to substantive questions - sometimes asking the same thing two or three different ways to make sure they were understood. Prospective jurors who knew one of the principals or prospective witnesses, who may have been influenced by publicity about the case, or who just felt they could not render a fair verdict were questioned privately.

Some were excused, others survived to be cut shown by preemptive challenges.

At 10:50 yesterday morning the jury of 12 and the six alternates had been picked. They stood in the jury box facing Antonelli and Yeldell, who also stood, as the clerk entoned the oaths. After the jurors had sworn to render an honest and fair verdict, Gesell gave them their charges:

"You are the sole judge, you are the only judge of the facts," he said.