In 1991, the Colombo crime family in Brooklyn went to war with itself: a rebel faction tried to seize control of the family from its boss, Carmine Persico, who was serving life in jail. Gregory Scarpa, Sr., a sixty-three-year-old mobster, immediately took command of the armed faction loyal to Persico. Scarpa was seriously ill: as the result of a blood transfusion, he was H.I.V.-positive. His body had shrivelled from a muscular two hundred and twenty-five pounds to a gaunt one-fifty, his stomach had been removed during surgery, and he digested his food with pancreatic-enzyme pills. Yet Scarpa, a multiple murderer, hadn’t slowed down. During the seven months that the shooting war lasted, he could be seen driving with his troops along Avenue U, in Brooklyn, scouting out the social clubs and bars where members of the enemy faction were likely to be found. Sometimes he drove past the rebels’ houses, and one night he surprised a rebel who stood on a ladder, with his back turned, hanging Christmas lights on his house. Scarpa rolled down his car window, stuck out his rifle, and picked the man off with three shots. Then he paged his consigliere with the satanic code 666, to signify a fresh kill.

By the time the war ended, in June, 1992, ten people had died, including an innocent man of eighteen who was shot accidentally at a Brooklyn bagel shop. Ten more people had been wounded, among them a fifteen-year-old bystander, who was shot in the head. By far the most violent participant in the war was Scarpa: he murdered four people and wounded two.

At the Manhattan office of the F.B.I., squads had been in place since the eighties to investigate all five New York Mafia families. The supervisor of the squad for the Colombo and Bonanno families was R. Lindley DeVecchio, a dapper, curly-haired man of average height, with a mustache, whom friends and colleagues called Lin. He was a well-liked veteran who had been with the Bureau since the J. Edgar Hoover era, and he had come up through the New York office as an older colleague of Louis Freeh, the current F.B.I. director. The Colombo war presented a unique challenge to DeVecchio. The F.B.I. had a duty to try to prevent violence of every type, even among criminals. If it could learn, perhaps from an informant, when and where a hit team was to be mobilized, the shooters could be intercepted in the act. DeVecchio did, in fact, have an informant inside the Persico faction of the Colombo family. That informant, however, was hardly likely to divulge the activities of the faction’s hit team, for the simple reason that he was its leader—Gregory Scarpa himself.

Scarpa had had a secret relationship with the F.B.I. since the early nineteen-sixties, though for two extended periods he had been “closed,” which is to say that he and the Bureau had had a falling out, and no agent was authorized to make contact with him. In 1980, DeVecchio had taken the initiative to seek out Scarpa, win back his good graces, and reopen him for the first time in five years. It had been a spectacular career move. Scarpa was no ordinary informant; he was classified as a T.E., for “top echelon,” source. DeVecchio was promoted to squad supervisor in 1983. Largely because of his work with Scarpa—and with a second, unidentified mobster, it was said—DeVecchio became one of the Bureau’s most admired experts on dealing with informants, and was accorded the honor of being asked to teach informant development to recruits at the F.B.I.’s training academy, in Quantico, Virginia.

DeVecchio told his students that when it came to building a rapport with an informant, training alone was no substitute for having the right personality. He was a natural himself, even if his upbringing—he is a native of Fresno, California, and the son of a decorated Army colonel buried at Arlington National Cemetery—could not account for it. DeVecchio had become a flashy dresser: at work, he wore a gold bracelet, silk pocket squares, and shirts with monograms. He was also an avid gun collector. He had learned the moves and the jargon of mafiosi on the streets of New York, and he was proud of it. “I’ve spent virtually twenty-nine years of my life talking to wise guys,” he said recently. “You either know how to talk to them or you don’t. Many a competent agent doesn’t have the street sense.” DeVecchio, who has a coarse sense of humor, recalled that his standard opening remark to the students was “I have two college degrees, and my vocabulary has degenerated to four-letter words, and if that bothers you—_fuck you!”

Even agents with the keenest street sense might have found it intimidating to deal with Scarpa, an imposing man with a deep voice, who once said of himself, “The sign of my birth is Taurus, which is a bull,” and who, in a wiretapped conversation during the eighties, convincingly made pronouncements such as “I don’t have my money by Thursday, I’ll put him right in the fucking hospital.” Whatever chemistry existed between him and Lin DeVecchio, it was strong. Informants are supposed to be handled by two agents at a time, and the Bureau discouraged anyone of supervisory rank from operating an informant. Those guidelines were waived for DeVecchio because, he insisted, that was how Scarpa wanted it—there was no other agent he trusted. For more than a decade, DeVecchio was almost always unaccompanied when he met with Scarpa—at an apartment rented by the F.B.I. or in a hotel room, or at some other prearranged location. Sometimes DeVecchio delivered cash to Scarpa. The two men left each other phone messages as “Mr. Dello,” their shared code name, and spoke frequently via a special telephone at the F.B.I. building called the hello line, which could not be traced. F.B.I. reports show that during the seven months of the Colombo war they met or spoke, on the average, at least every ten days.

During the war, DeVecchio maintained that Scarpa was not an active participant, but some younger agents were hearing repeated reports to the contrary. They were alarmed. In 1980, the Department of Justice had issued detailed guidelines: if an informant was suspected of involvement in any “serious act of violence,” the supervisor in charge was required to consider closing him and targeting him for arrest. While it was understandable that DeVecchio might be reluctant to close a top-echelon informant—particularly someone who had helped make his career—that seeming reluctance put him at odds with some of his own agents. Eventually, four of them reported to the Bureau that, in an apparent effort to protect Scarpa not merely from arrest but from his enemies in the Mob, DeVecchio had leaked sensitive, confidential information to him. One agent has alleged that DeVecchio became compromised to the point of helping Scarpa locate people that Scarpa wanted to kill.

In early 1994, DeVecchio was placed under investigation, but in the meantime he was neither discharged nor put on administrative leave. Instead, he was moved off his squad to another supervisory position—as the F.B.I.’s drug-enforcement coördinator for the entire Northeastern United States, with unrestricted access to classified documents. He continued to hold that job after he informed the Bureau in a sworn statement that he was not amenable to a voluntary polygraph examination, and, incredibly, even after invoking his Fifth Amendment privilege and refusing to testify about his conduct as an F.B.I. supervisor at a hearing last May. No F.B.I. official—not even Louis Freeh or the New York chief, James Kallstrom—would comment on why a man being investigated for leaking information was kept in a post requiring top-security clearance. Douglas Grover, DeVecchio’s lawyer, says it is because the Bureau had always understood what DeVecchio was doing to protect a valuable informant, and had approved of his actions. “Whatever Lin did, he did it as an agent of the institution, both literally and figuratively, acting on behalf of the F.B.I.,” Grover says.