The prosecution and the defense in D.C. Mayor Marion Barry's drug and perjury trial pursued fundamentally different tactics in the two weeks of jury selection that ended Friday.

Neither was quite conventional and neither was without risk, but each appeared to secure most of its goals.

For Assistant U.S. Attorneys Judith E. Retchin and Richard W. Roberts, the name of the game was information. The two prosecutors wanted everything they could squeeze from prospective jurors, and they were willing to risk annoying them to get it.

For defense lawyers R. Kenneth Mundy and Robert W. Mance, the goal appeared to be to establish a rapport with the prospective jurors, but to leave most of the jurors' deepest feelings unexposed. The defense lawyers seemed to be willing to risk missing a pro-prosecution die-hard in the process.

The diametrical game plans reflected this common understanding of the case: Prosecutors, to secure a conviction, need 12 jurors on their side. The defense can avoid conviction with only one. Everyone would rather win than lose, but an indecisive outcome -- a hung jury and mistrial -- favors the mayor.

Simple enough, that arithmetic holds true for any case. But prosecutors, according to people familiar with their thinking, see special risks -- and the defense sees special opportunities -- in a case as charged with passion as Barry's.

Roberts and Retchin made few attempts to project warmth or approval in their interaction with the panelists. Roberts, known for a dry wit among friends, cracked no jokes -- not even when, in a slip of the tongue, he referred to the defendant as "Mr. Guilty."

Instead, the prosecutors searched for bias. They knew that panelists have many reasons for keeping their thoughts to themselves in the intimidating setting of a courtroom. Some are shy. Some are inarticulate. But what the prosecutors feared most was deliberate concealment.

Carl Wallace, a black man dressed in working-class plaid, took the stand Thursday in a demeanor of amiable patience. No, he did not know the witnesses. Yes, he understood the presumption of innocence. No, he had no opinions about the case.

But Wallace kept his hand on his face. Roberts thought he heard hesitation in his voice, and asked about it. "That's just my way of life, hesitating," Wallace said.

After four or five questions about the Vista Hotel, Wallace hadn't budged from his neutrality. But when Roberts asked whether Wallace saw an invasion of privacy in the FBI sting against the mayor, the witness creased his brow and narrowed his lips.

"I do," Wallace replied, "and what's more, it's a waste of money."

Wallace was transformed, answering crisply and with heat from that point on. "Yes," the opinion was strongly held. "Correct," he would carry it with him throughout the trial. "Without any question," he would advance it in the jury room.

U.S. District Judge Thomas Penfield Jackson excused the man from further service. Roberts and Retchin made similar probes of nearly every panelist.

Mundy and Mance asked less than half as many questions in the course of the two-week jury selection. Without a standard line of inquiry, they probed only when they sensed a specific bias. Panelist Jackie Chism, for example, had split with her husband over drugs. Another woman, whose name was inaudible, used language suggesting strong feelings about marital infidelity. But generally the panelists got this message from Mundy and Mance: We are satisfied with you.

Sometimes, after a lengthy prosecutorial interrogation, Mundy said, "I have no questions, your honor," with emphasis on the "I."