It was the worst possible outcome of an undercover drug buy. It happened in Southwest Washington nearly two years ago: Eric Butera, an informant working with D.C. police, was attacked by three men and stomped to death.

Although the alleged assailants have been convicted, Butera's mother believes others share responsibility. She's in U.S. District Court in Washington this week, pursuing a $115 million civil lawsuit against the D.C. police department.

Terry Butera's lawsuit maintains that D.C. police enlisted her son in a dangerous operation and didn't take appropriate steps to protect him, then were nowhere to be found when he was beaten and robbed. She has targeted the D.C. government as well as the four police investigators on the case.

The trial, which began Tuesday, focuses on an unseemly aspect of law enforcement that usually gets little public attention. Although police routinely use informants to help them develop cases, often by making undercover drug buys, the informants rarely are killed. Butera's death calls into question the procedures used by D.C. police, at least on the night of Dec. 4, 1997.

Peter C. Grenier, the family's attorney, told jurors in opening statements that Butera suffered "the most ghastly, excruciating death one can imagine," adding, "Terry Butera doesn't want your sympathy. She wants justice."

Assistant Corporation Counsel Thomas L. Koger countered that protecting Butera was a top priority for police and that each step of the operation was reviewed with the informant. Police "never abandoned" Butera, Koger insisted.

"These controlled buys are done on a daily basis in the District of Columbia and you never hear of them," Koger said. "This one is a horrible exception, and it's a horrible exception because on this night three monsters savagely attacked Eric Butera. . . . Eric Butera was the victim of opportunity."

Butera, 31, who had a history of drug abuse, was attempting to turn his life around when he went to police saying he had information that could help them solve a triple slaying at a Starbucks coffee shop. According to Butera, he had overheard people talking about the slayings several months earlier when he bought drugs in a row house in the 1000 block of Delaware Avenue SW.

Homicide detectives, who at the time were struggling to solve the Starbucks case, asked Butera to make another drug buy in the house so they could get a warrant to search the place. They gave him $80 in marked bills and drove him into the neighborhood in hopes he could buy crack cocaine.

Yesterday, two of the supervisors on the detail--Lt. Brian McAllister and Sgt. Nicholas Breul--defended themselves as Grenier and co-counsel Saul Jay Singer attacked their handling of the operation. The lawyers contended that police were not in position to see Butera and should have equipped him with a monitor or transmitting device that would have alerted them to any trouble.

McAllister testified that Butera told police he had worked as an informant in the past and was comfortable with the arrangements. McAllister said the plan called for Breul and detectives Anthony Brigidini and Anthony Patterson to be in the area but far enough away from the row house that they wouldn't generate suspicion. Breul testified that he and Patterson were roughly a block away in one car and that Brigidini was nearby in another. Breul said he and Patterson unrolled their car window in case there were any "screams or gunshots."

As it turned out, Butera was turned away at the house. While making his way back into the courtyard, he was attacked by two men, who left him bleeding on the ground. Moments later, a third man came by and repeatedly kicked him in the head. None of the detectives was in position to see the beatings, and it wasn't until 40 minutes after Brigidini dropped Butera off that they even realized something was wrong. A neighborhood resident called 911, and patrol officers, not the detectives, were the first to discover Butera's body.

McAllister, who was at the homicide unit's headquarters that night, testified that Breul called him and said, "They killed our source."

Breul testified he and Patterson drove through the area, as did Brigidini, but they didn't see anything in the darkness. Acknowledging that Butera told police he usually completed his drug deals within 15 minutes, Breul testified, "in hindsight, a time limit should have been set, yes."

Grenier maintained that that was one of many lapses contributing to Butera's death and that police violated at least 10 departmental orders. The department later launched an internal investigation and decided against pursuing disciplinary action against the supervisors or detectives. Over the next week, the trial in Judge June L. Green's courtroom will delve into the views of experts on police tactics. Brigidini and Patterson are to testify today.

Although Butera's tip looked promising at the time, officials said no one in the house had anything to do with the Starbucks case. Another suspect, Carl Derek Havord Cooper, is awaiting trial on federal murder charges.