It is 20:28:17 on the Vista Hotel videotape, 42 seconds after the FBI burst in. D.C. Mayor Marion Barry is against the wall, a roomful of agents encircling him. Off to one side, an agent walks to the dresser and opens a drawer.

"Stop the tape right there!" commanded defense lawyer Robert W. Mance. "Did you see that?"

What the jury and the witness, FBI agent Frank O. Steele, saw on the courtroom monitor at that moment on Friday was another FBI agent caught in freeze-frame with the drawer open, an image Mance showed as if it were a picture of a child with his hand in a cookie jar.

Steele had testified that he opened that drawer and found two crack pipes in an eyeglass case at 10 p.m.

But here was Mance showing another agent opening that drawer at 8:28 p.m.

As discrepancies go, it was no bombshell. There was no evidence that the agent on the tape knew what the eyeglass case contained. But there were some unspoken messages conveyed by Mance. Why did it take the FBI so long to find such a simple item? What else might these agents have done? Tamper with evidence, perhaps?

With the government's case in Barry's perjury and drug conspiracy trial at the halfway point, the contours of Barry's defense are apparent. It is not a frontal assault, but a guerrilla war -- sniper shots aimed, for the benefit of a mostly black jury, at an agency that historically has been viewed by some blacks as an enemy of the civil rights movement: the FBI.

The attack began at the outset of the trial, when the mayor's lead attorney, R. Kenneth Mundy, told the jury the case would be about "deals the government made with the devil." At the time, it seemed that Mundy was referring to former Barry friends who became informers. But as the trial goes on, he sounds increasingly as though the devil has three initials.On the same day Mance exposed the FBI's inability to locate quickly the crack pipes used during the Vista sting, he also bore in on the fact that the FBI didn't find a small rock of crack in an inside pocket of Barry's jacket until Jan. 29, 11 days after the Vista sting. Although Steele said he searched the jacket at the arrest scene, he testified that he overlooked that pocket. The crack was discovered by Frances Henning, an FBI evidence technician in the agency's Hair and Fibers Unit. In his cross-examination of Hazel Diane "Rasheeda" Moore, the woman who lured Barry into the Vista sting, Mundy made a point of asking Moore who has been feeding her, clothing her, caring for her children and paying for her lodging in "first-class hotels." Her answer, time after time: "The FBI." Last week, the defense withdrew from an agreement not to challenge the "chain of custody" of evidence from the Vista Hotel, usually a routine defense concession in a drug case. By refusing, Mundy forced prosecutors to call as witnesses every person who ever had control over a piece of evidence, all of them so far from the FBI, to testify that they had not tampered with it. In his cross-examination of Moore, Mundy also peppered her with a series of questions about the Vista tape. Why was the television on so loud? Why was there no sound on a tape of her in the bathroom? Why did she and FBI agent Wanda Moore use hand signals? Why did Rasheeda Moore move the chair that partially blocked the camera that caught Barry smoking crack? Without challenging anything the tape actually showed, Mundy managed to imply sinister conspiracies.

There is no way to tell how successful these tactics have been with the jury. But trial-watchers in the criminal justice bar say that theme may resonate with a jury in which 13 of 18 jurors and alternates are black. Many blacks say there are historical reasons to be skeptical of the agency that J. Edgar Hoover created.

"There's only one recurring perspective on the FBI in most of the black community," said Charles J. Ogletree Jr., a Harvard law professor and former public defender who is following the Barry case closely. "The FBI is associated with . . . the COINTEL program that led to the elimination and destruction of the Black Panther Party, and to the infiltration of some very legitimate and basic civil rights activity of many of the important leaders of the black community."

Ogletree emphasized that for Barry to be acquitted he need not convince the jurors that the FBI misbehaved. "All they have to believe is that they have not been convinced it didn't happen that way," he said. "If one or two jurors' questions aren't answered, I am convinced that they will refuse to return any verdict of guilty."

Black opinion, on the other hand, may be more difficult to predict. The Barry jury includes black people who, during jury selection, expressed opposite views on the use of undercover stings. One woman said she favored stings because they help police and the FBI "catch criminals." Another said, "Anything undercover is wrong."

So far, Mundy has failed in his attempts to challenge directly some evidence against the mayor: the image of Barry smoking crack, blood and urine tests revealing cocaine use, and a growing list of witnesses who say they used drugs with the mayor or in his presence.

But prosecutors have found it difficult to fight Mundy's guerrilla war.

On Thursday, Assistant U.S. Attorney Richard W. Roberts complained at a bench conference that Mance and Mundy were trying to make an "unfair inference" to the jury that "there was something suspicious" in the way the FBI handled the evidence of Barry's drug use.

The next day, when Mance showed the tape of the agent opening the drawer, he was careful to begin where a swarm of men, wearing jackets with "FBI" emblazoned in big letters, bolted into the room and held the black mayor of the nation's capital against the wall.

Then he played it again. And again.

Staff writer Jill Nelson contributed to this report.

The following are the 14 charges against D.C. Mayor Marion Barry and a summary of the evidence offered so far on each. The government, which must prove each charge beyond a reasonable doubt for conviction, has not finished presenting its case. Barry will offer defense evidence, if he wishes, after the government rests.

Count 1 Conspiracy to possess cocaine, Fall 1984 to Jan. 18, 1990.

Because every alleged act of possession is part of the conspiracy case, most of the prosecution's evidence on counts 2 to 14 is relevant. Additional evidence: logs of telephone calls Barry received from alleged co-conspirators and testimony by Hazel Diane "Rasheeda" Moore about "more than 100" episodes of drug use for which Barry has not been separately charged.

Count 2 Possession of cocaine, November 1987.

No evidence presented so far.

Count 3 Possession of crack cocaine, Sept. 7, 1988.

Lydia Pearson testified she sold three $30 bags of crack to Barry at the Frank D. Reeves Center on Sept. 7, 1988, the date written on a job application she said she gave to Barry the same day.

Count 4 Possession of crack cocaine, Dec. 16, 1988.

Charles Lewis testified that Barry arrived for a visit at the downtown Ramada Inn carrying a matchbox full of crack. Lewis said they smoked it.

Barry's defense sought to discredit Lewis -- on this and the following counts -- by eliciting inconsistencies on details and emphasizing that he testified against Barry in the hopes of a more lenient sentence for his own drug convictions.

Count 5 Possession of crack cocaine, Dec. 17, 1988.

Lewis testified that Barry again brought crack to the Ramada, this time in the cuff of a trouser leg. The two of them, Lewis said, improvised a crack pipe from a sherbet glass and aluminum foil. Lewis said Barry gave him $60 to buy more crack when the supply Barry had brought was exhausted. Lewis also testified that Barry removed a bathroom lightbulb, for the second day running, because he thought it might be a surveillance device.

Count 6 Possession of crack cocaine, Dec. 19, 1988.

Lewis testified that Barry sent $100 to the Ramada so that Lewis could buy a "working fifty," a wholesale quantity of crack. Lewis, who could not find a working fifty, said he bought two $20 packets of crack and invited James McWilliams to meet Barry in the hotel room. He said three men watched a Monday night football game, with Barry joining Lewis in the bathroom periodically to smoke crack. McWilliams testified that he did not see Barry smoke crack but saw him with smoking paraphernalia in the bathroom and smelled the smoke. McWilliams said he tried to engage Barry in a business conversation, and Barry replied that McWilliams looked like Santa Claus.

Barry's defense sought to discredit McWilliams by pointing out that McWilliams had struck a deal with prosecutors in which he pleaded guilty to minor charges but avoided more serious prosecution in exchange for testimony against Barry.

Count 7 Possession of crack cocaine, Dec. 22, 1988.

Lewis testified that he offered crack cocaine to a Ramada maid, who declined. A hotel executive, Sukhjit Singh, testified that he arranged for police to investigate the maid's report. Undercover officers were about to approach Lewis, Singh said, when the hotel discovered that Barry was in the room and Singh asked the officers to leave.

Lewis testified that Barry brought a crack pipe in an overnight bag and that the two men smoked crack with it. After Barry left, Lewis said, a Washington Post reporter arrived to ask about allegations that police had called off a drug investigation upon discovering that Barry was in the hotel.

Count 8 Perjury.

This charge centers on Barry's denial, in January 1989 grand jury testimony, that he knew anything about Lewis's involvement with drugs. The evidence includes Barry's tape-recorded testimony, contradicted by the testimony of Lewis and McWilliams in Counts 4, 5, 6 and 7. Four women -- Jonetta Vincent, Dixie Lee Hedrington, Zenna Matthias and Linda Creque Maynard -- gave direct or circumstantial evidence in support of Lewis's testimony that Barry observed or participated in Lewis's drug use in the Virgin Islands.

During cross-examination, Barry's defense called attention to inconsistencies in the witnesses' accounts, and emphasized that each of the witnesses had agreed to testify against Barry in in exchange for or in hopes of -- more lenient treatment by the government.

Count 9 Perjury.

This charge centers on Barry's denial in grand jury testimony that he ever gave Lewis any drugs. The evidence is Barry's tape-recorded testimony, contradicted by the testimony of Lewis and McWilliams in Counts 4, 5, 6 and 7.

Count 10 Perjury.

This charge centers on Barry's denial in grand jury testimony that he ever received any drugs from Lewis at the Ramada. The evidence is Barry's tape-recorded testimony, contradicted by the testimony of Lewis and McWilliams in Counts 4, 5, 6 and 7.

Count 11 Possession of cocaine, Aug. 26, 1989.

No evidence presented so far.

Count 12 Possession of cocaine between Nov. 7 and Nov. 10, 1989.

No evidence presented so far.

Count 13 Possession of cocaine between Jan. 1 and Jan. 18, 1989.

No evidence presented so far.

Count 14 Possession of crack cocaine, Jan. 18, 1990.

The FBI's Vista Hotel videotape, which shows Barry taking two long drags from a crack pipe, is the prosecution's centerpiece on this count. This is also the only count for which prosecutors offered physical evidence of drug possession: two crack pipes and a leftover rock of crack. Rasheeda Moore, who appears with Barry on the tape, testified that he came to visit her hotel room, used "coded" language to request crack, and smoked it. Because prosecutors must combat Barry's entrapment defense by proving he was predisposed to commit the crime, the evidence in counts 1-7 and 11-13 is also relevant.

In cross-examination, Barry's defense suggested that Moore had induced Barry's crack use and entrapped him in the crime. The defense challenged Moore's credibility on many details, including the question of who brought up the subject of drugs. The defense also pointed to deals Moore struck with the government and the money she has received while in the federal witness protection program. Compiled by Barton Gellman