U.S. District Judge Joseph L. Tauro gave Connolly the maximum sentence under federal guidelines that called for a sentence of eight years, one month to 10 years, one month.

In recent weeks, the judge was deluged with 200 letters from friends of Connolly asking for leniency. He also received letters asking for a stiff sentence, including one from Robert Jordan, assistant director of the FBI Office of Professional Responsibility, who said Connolly had "betrayed his oath of office, his duty to his fellow agents, and his brothers and sisters in law enforcement."

Connolly, 62, declined the opportunity to speak at the sentencing hearing. He blew a kiss to his wife and other family members seated in the front row as he was escorted, without handcuffs, from the courtroom. Under federal rules, he must serve at least 8.5 years of his sentence.

Connolly was considered a star agent for his help in breaking the New England Mafia in the 1970s and 1980s by using information he got from top-echelon FBI informants James "Whitey" Bulger and Stephen "The Rifleman" Flemmi, leaders of the Winter Hill Gang.

But a jury found that Connolly become too close to his informants and went too far to protect them.

Connolly was convicted in May of racketeering, obstruction of justice and lying to an FBI agent for tipping off Bulger and Flemmi about criminal investigations and warning them about an upcoming indictment in 1995.

Bulger fled and remains a fugitive on the FBI's "Most Wanted" list. Flemmi is serving a 10-year prison sentence for money laundering, extortion and obstruction of justice. He is awaiting trial for his alleged role in 10 murders.

Connolly's trial exposed embarrassing conduct by the FBI. His former supervisor, John Morris, testifying under a grant of immunity, admitted pocketing $7,000 in bribes from Bulger and Flemmi. The FBI suspended another agent, John Newton, during the trial after a Bulger crony testified that Newton had accepted a $1,000 bribe from Bulger.

Last year, the Justice Department issued stricter guidelines for handling criminal informants as a result of the Boston case.

Documents obtained by The Associated Press in July showed a pattern of conduct in the FBI that went beyond Connolly and a few other agents in Boston.

Field memos showed that for more than 20 years, FBI headquarters in Washington knew that its agents in Boston were using professional killers and mob leaders as informants and shielding them from prosecution for serious crimes, including murder.

Special U.S. Attorney John Durham urged Judge Tauro to consider the damage Connolly had done to the FBI's reputation. Durham also scoffed at Connolly's claims that he didn't realize while he was the FBI's handler for Flemmi and Bulger that they were committing serious crimes, including murder.

"That is preposterous on it face," Durham said.

He urged the judge to impose a sentence that would show the public "that there are no special rules for those people who are well connected."

Connolly's lawyer, Tracy Miner, said Connolly cultivated Bulger and Flemmi as criminal informants at the urging of his FBI superiors.

"Did he become too close to Mr. Bulger and Mr. Flemmi? Obviously he did, but that was the position the FBI placed him in," she said.

Tauro said he imposed the maximum sentence because he wanted to show the justice system's "zero tolerance" for someone who obstructs justice.

Charles Prouty, special agent in charge of the Boston FBI office, said Connolly had "damaged the bond of trust" the FBI has with the public.

"We must work hard to regain that trust," Prouty said.

The judge rejected defense requests that Connolly be freed on bail pending appeal. Instead, the judge granted a prosecution request to revoke Connolly's bail. Connolly was taken into custody immediately to begin serving his sentence.