The plea bargaining was long and difficult. The defendant, Peter Rollock, the leader of a Bronx narcotics gang, had been charged in seven killings. Federal prosecutors wanted the death penalty; any plea deal would have to include a mandatory life sentence.


But prosecutors had another demand: because Mr. Rollock, then 25, had been accused of ordering some of the killings from jail, he would be placed in solitary confinement and barred from communicating with virtually all outsiders.


Pistol Pete, as Mr. Rollock was known, agreed to the deal, and in late 2000, he was sent to the federal Supermax prison, as the Administrative Maximum, or ADX, facility in Florence, Colo., is known, and where some of the nation’s most infamous criminals are housed. With that, he might have retreated from public view forever.


But Mr. Rollock, now 37, has not retreated. In his nearly 12 years in isolation at the Supermax, he has maintained a spotless record, his lawyers say. He has spent countless hours taking adult education courses through a closed-circuit television in his cell. He has even written a novel, “Trigga,” described by his lawyers as a cautionary tale for young gangsters. His family self-published the book; it is available on Web sites like Amazon.com.


Still, Mr. Rollock’s behavior has not led to the most important change he seeks: relaxing the harsh conditions of his confinement and allowing him to enter the prison’s general population.


Although Mr. Rollock’s deal with the government mandated a review of his status after 18 months, the Bureau of Prisons has consistently refused to ease the restrictions, even though one Supermax supervisor recommended in 2005 that he be placed in the general population.


Federal prosecutors have not wavered in their concerns. To them, Mr. Rollock was a ruthless killer whose gang, Sex, Money and Murder, or S.M.M., terrorized parts of the Bronx and made its presence felt everywhere, “in the shot-out streetlights, the bullet-riddled buildings and the graffiti with which S.M.M. members memorialize their gang on every available wall,” the government has written.


The prosecutors argue that their concern about Mr. Rollock’s ability to communicate with outsiders, or even with fellow prisoners, is well founded. They have said in court, for example, that while Mr. Rollock was jailed in New York before his sentencing in November 2000, he gave an interview to a magazine that is popular in prisons and disclosed the names of former gang members who had cooperated against him; as a result, the government says, it had to place people in the witness protection program.


“Mr. Rollock’s name still has significant cachet on the streets in the Bronx,” a prosecutor at the time, David M. Rody, told a judge in 2010. He said that he had no doubt what would happen if Mr. Rollock decided to place “a hit” on a witness and the message got out to his gang.


“I am not saying he is ordering anything,” Mr. Rody said, “but our concern is that if he did, these people would act on it in a heartbeat.”


Mr. Rollock spends 23 hours a day in his cell at the Supermax, and is allowed one hour for exercise. He receives meals through a slot in his door. He is allowed limited calls.


“To me, it’s inhumane to keep anybody in solitary confinement for this long,” Avraham C. Moskowitz, one of Mr. Rollock’s lawyers, said. “He’s done everything they’ve asked of him,” Mr. Moskowitz added. “My concern is that he’s going to lose his mind.”


Mr. Rollock’s story is not that of an innocent man wrongly convicted. When he pleaded guilty in 2000, he admitted in Federal District Court in Manhattan that he had led the violent S.M.M. gang, which had sold crack cocaine and heroin in the Bronx as well as in Pittsburgh and North Carolina.


“We possessed firearms and committed murder,” he told Judge Miriam Goldman Cedarbaum, describing killings he had carried out or approved from jail.


In one 1993 case, he said, he fatally shot a man who had drawn his gun on a fellow gang member. “We protected one another,” Mr. Rollock explained.


In another case, in 1994, he was entering a sneaker store when he saw an associate of another of his recent victims. He fatally shot him, too. “I knew that he was a danger to me,” Mr. Rollock said.


While Mr. Rollock (whose name has also been spelled Rollack) was jailed at Rikers Island around late 1995, a federal indictment charges, he joined the Bloods gang and made S.M.M. a kind of local affiliate.