D.C. Mayor Marion Barry's defense lawyer, R. Kenneth Mundy, in vigorous interrogation of the lead FBI agent in Barry's case, yesterday attacked the bureau for the Vista Hotel sting, demanding to know why agents let Barry smoke crack instead of arresting him when it was in his hand.

Mundy waited until near the end of his case to question FBI Special Agent Ronald Stern in what the defense hoped would be a dramatic showdown that would leave the jury with a sense of outrage over the actions of the FBI.

Instead, Stern challenged many of Mundy's questions with an allegation that Barry himself was responsible for his drug use at the Vista.

Earlier, U.S. District Judge Thomas Penfield Jackson prevented Mundy from asking his most pointed questions: about the government's reasons for targeting the mayor for arrest, and the time and money it expended to do it.

Mundy made a last attempt to get around the judge's earlier ruling, arguing at a bench conference that Stern is the vanguard of a secret FBI effort to prosecute black public officials across the country.

An FBI spokesman yesterday strenuously denied that the bureau has any such agenda. FBI spokesman Jim Mull said that "any allegation the FBI has a team of agents moving throughout the nation targeting black officials for investigation is unfounded and categorically denied."

If the defense rests and prosecutors complete their rebuttal case today, Jackson is expected to schedule closing arguments for Monday, with jury deliberations starting Tuesday.

At a morning bench conference, Mundy told Jackson that the defense had evidence that Stern had been involved in an effort to conduct a sting operation against former Atlanta mayor Andrew Young and former Georgia state senator Julian Bond, both of whom are black. Mundy also said Stern had been involved in similar actions against black officials in Chicago.

The jury did not hear Mundy's allegations. Assistant U.S. Attorney Judith E. Retchin told the judge that the statement was so "outrageous" that the transcript should be sealed.

"I will not seal this," Jackson said to Retchin, according to a transcript. "These allegations are simply going to have to get aired and responded to in the public forum."

Mundy repeatedly asked Stern why the agents did not interrupt the Vista sting once it was clear that Barry had the crack he bought from Hazel Diane "Rasheeda" Moore.

Stern replied that the FBI was wary that Barry would be able to talk his way out of a simple cocaine possession charge.

"There were too many plausible questions that he could have raised at that time," Stern said. "Number one is, we could have walked into the room to take custody and he could have called his security people and said, 'This lady wanted drugs, have her arrested.' "

Mundy asked Stern why Moore had been given intructions to try to keep Barry in the hotel room. Stern said it was because that was where the FBI could best monitor what was going on.

"She was supposed to keep him there because it was there that the trap was supposed to spring, right?" Mundy asked.

Stern resisted characterizing the FBI's actions that way. Eventually he replied that Moore had been told to try to keep Barry there "because the operation would be more effective" if it was limited to the one room.

Throughout the afternoon, Mundy framed his questions for maximum impact on the jury, regardless of what answers he got. In his lexicon, FBI agents looked through a "peephole" at Barry and Moore and were "fanning the flames" in Room 727.

At other times, the mayor's attorney openly battled with his FBI witness.

Stern was forced to concede that Barry's initial interest when he came to Moore's room was sex, not drugs. But, Stern said during a heated exchange with Mundy, the mayor mentioned drugs right off the bat when he asked Moore if she had "been good," a reference Moore said referred to drugs.

"Initially, when Mr. Barry arrived, he did ask Rasheeda if she has been good."

"We are back to that?" Mundy asked sarcastically. "That is the whole linchpin, isn't it?"

"It is part of it," Stern replied. "I believe it is a very important part."

About midway through the afternoon, Mundy tried to ask Stern about paramedics assigned to the Vista sting -- a question aimed at reminding the jury that smoking crack could have endangered Barry's health.

Retchin objected at a bench conference that the subject "is inflammatory because it deals with Mr. Barry's health." Mundy eventually was allowed to ask who decided to call the paramedics.

As the day wore on, an increasingly irritable Jackson frequently admonished Mundy to "move on" in his questioning, and the proceedings often were stalled by lengthy bench conferences. In one, he said Mundy was "fishing" with one witness.

In recent days, the judge has suggested the trial has lasted too long. At a bench conference on Wednesday, Jackson criticized Assistant U.S. Attorney Richard W. Roberts for his lengthy questioning of Carmen Benjamin. At issue was her claim that she had been pressured by the government after she told agents she had not seen Barry use drugs on a 1986 pleasure cruise.

"Has it ever occurred to you that you might be over-trying your case?" Jackson said to Roberts.

Yesterday, the judge said he no longer would permit attorneys to argue their objections at bench conferences. He ordered lawyers to state brief reasons for their objections in front of the jury, from their counsel tables.

At the end of the session yesterday, Jackson dismissed the jury early and gave the attorneys a lecture.

"Counsel, I am unhappy with the pace at which this matter is proceeding," he said. "I am unhappy with what I consider to be unnecessary, if not frivolous, objections. I am unhappy with the excessive zeal with which these matters are being argued at the bench, and this process is going to have to conclude . . . . Have I made myself clear?"

Meanwhile yesterday, the D.C. police department issued a strong denial of a Washington Times article saying that officers have been told to make sure their riot gear is in order, and that other preparations have been made in anticipation of a riot after a verdict in the Barry case.

Lt. Reginald Smith, a police spokesman, said checks of equipment are standard procedure, and are not made to prepare for a riot. "It is most unfortunate that a news agency would publish such an unsubstantiated story based on erroneous information and speculation," Smith's statement said. "The story is absolutely false, and does a great disservice to the entire community by raising the specter of violence."

Staff writers Gabriel Escobar, Barton Gellman and Elsa Walsh and staff researcher Ben Iannotta contributed to this report.