Running informants is 'like a circus and if the circus is going to work you need to have a guy in there with the lions and tigers. That was me'Did an Irish-American FBI agent become as violent and corrupt as the mobsters he had pledged to hunt down? Did John Connolly crave gangster recognition and use his position to destroy the Cosa Nostra - only to allow the Irish mafia to take over Boston's mean streets? Anna Mundow has been following his trial

It was just like old times. There was Mafia hitman John Martorano joking about one of the guys he whacked by mistake. There was "Cadillac" Frank Salemme fondly recalling the night he was inducted into The Family, and had blood drawn from his trigger finger. Over the past two weeks, a procession of large men in tight suits took a stroll down a blood-spattered memory lane in Boston. The boys were back in town. And they had all turned up to talk about their old pal, John Connolly.

But Connolly's most important guests - James "Whitey" Bulger and Stephen "The Rifleman" Flemmi - couldn't make it. Flemmi's in jail, doing 10 years for racketeering and awaiting trial on 10 murder charges. Bulger is on the run with a $1 million reward on his head. As a Boston policeman in the foyer remarked to me: "You make a living bashing people, you're gonna make enemies". Enemies and friends alike attended this wiseguy reunion. Offering possible immunity or time off their current sentences, the Federal Government ordered Salemme and others to share their memories of Connolly with a packed courtroom.

Connolly is not Italian. He is as Irish as an American can be; in Boston parlance, a Mick. He is also a retired FBI agent, a law enforcement star for more than 20 years who worked the New York streets with undercover legend Joe Pistone aka Donnie Brasco. John Connolly is not a gangster.

Well, maybe not a gangster. But he recently became the defendant.

Last week in Boston's Federal Courthouse, government prosecutor John Durham delivered the closing arguments in a momentous two-week trial that revisited the heyday of organised crime and law enforcement corruption in the heart of Irish America: South Boston - or Southie - where you stick with your own and never, ever, squeal.

In the case of Connolly and Bulger, however, the tribal code was discarded along with the FBI rules. Bulger, Southie's Godfather, became an FBI snitch and Connolly became a handler who went over to the other side.

Finally, in the ultimate career reversal, the agent who for decades employed the force of the federal government found that force turned on him as Durham produced chilling evidence of Connolly's role as "a member of a criminal enterprise" and as a key informant for Boston mobsters.

The stylish enforcer who became an FBI celebrity by recruiting notorious gang boss Bulger as an informant in 1975 was charged in 1999 not only with lying to investigators and obstructing justice but also with racketeering conspiracy, a charge which allows hearsay evidence in court and which released a flood of testimony from mobsters and lawmen.

According to the prosecution, Connolly tipped off Bulger and others to imminent indictments and "most distressingly" revealed the identity of other FBI informants to their executioners.

"Brian Halloran, killed. John McIntyre, killed. Dennis Callahan, killed," Durham told the jury, listing just a few of Bulger's - and, allegedly, Connolly's - victims.

"We're taking real good care of that guy," Bulger once remarked of Connolly, using the phrase in its non-lethal sense. Witnesses testified that Connolly was well rewarded for protecting Bulger's extortion rackets, allegedly receiving a diamond ring among other gifts and thousands of dollars in bribes. There were stacks of uncashed FBI paychecks, a large house in the suburbs, another on Cape Cod, a $40,000 boat.

But there was more than money involved. There was Southie, the most clannish enclave in Irish America, a green-hearted strip of land jutting defiantly out into Boston Harbour, largely resistant to gentrification and wary of outsiders.

John Connolly and Whitey Bulger grew up in the same public-housing block in South Boston, a neighbourhood that offered most youths a limited career choice in the 1940s and 1950s:work at the Gilette factory, become a fireman, a cop or a crook.

James and Jean Bulger raised six children in the Old Harbour housing project. The eldest, Whitey, became Boston's notorious crime boss and head of the Winter Hill Gang, overseeing a score of murders and countless rackets in a 25-year reign that ended when he fled as he was about to be arrested in 1995.

Bulger's younger brother, Billy, became the most powerful politician in Massachusetts, as head of the state Senate, and is currently president of the University of Massachusetts. Studious and ambitious, Billy was a childhood friend and mentor to John Connolly. Mafia killer John Martorano testified that, according to Whitey, Billy had "helped \ to stay on the straight road, to go to college, and not be a rogue". In return, Billy reportedly asked agent Connolly to "Just keep my brother out of trouble". (Billy Bulger denies the allegation.) Connolly could not keep Whitey out of trouble. But he could keep him out of jail - by persuading him to become an FBI informant in 1975 and by allegedly tipping him off 19 years later to federal indictments that named Bulger and several of his associates.

Throughout the 1980s, the Connolly/Bulger pact had a pleasing symmetry and an avowedly noble purpose. Bulger and Flemmi (already an FBI informant) would trade information on Boston's Italian Mafia in return for FBI protection. It worked. John Connolly, nicknamed Prince of the City, was credited with destroying La Cosa Nostra. And Whitey Bulger expanded his criminal empire, filling the vacuum left by the defeated Anguilo crime family.

Protect Bulger and his information sinks Anguilo. The deal sounded neat. No one expected it to be clean.

"I'd state right out that I'd kill them," Bulger henchman, Kevin Weeks testified last month under cross-examination. Appearing as a prosecution witness in the expectation of a reduced sentence, Weeks clearly enjoyed being the star attraction. "The idea of committing a crime is to get away with it," he joked, earning sniggers from the jury.

But defence counsel Tracy Miner finally stung him with her allegation that he had intimidated victims by producing body-bags at the critical moment during torture sessions. Being accused of murder was one thing, being accused of subtlety was another. "I didn't need to threaten with body-bags," Weeks insisted, flexing his shoulder muscles and straining his tailored suit.

He also disliked being called Bulger's driver. "You ever drive with Whitey Bulger?" he challenged the petite, bespectacled Miner. She had not. But she stuck to her automotive theme. Sceptical of Weeks's assertion that Bulger had once crossed town in 15 minutes, she even ventured her own little joke. Could Mr Bulger "make the traffic magically move and disappear?" To which Weeks replied: "Jim Bulger makes a lot of things magically move and disappear".

Connolly did not find Kevin Weeks funny. Unsmiling, he never took his eyes off the witness. When Weeks told of once handing Connolly an envelope containing $5,000 from Bulger, Connolly's stare intensified.

Allowed by US District Judge Tauro to sit with his wife, his three sons and his sister in a spectator bench throughout the trial, Connolly was the only person to endure weeks of testimony without squirming on the uncomfortable seats.

Squirming is not John Connolly's style. The bulky 61-year-old with a weakness for expensive suits and lacquered hairstyles strode up to the vast courthouse on Boston's Waterfront each day flanked by his glamorous second wife and his brother, a retired Drug Enforcement Agency agent.

"I knew the whole family growing up," the father of one of the defence lawyers told me, visibly relaxing when he learned that I was Irish. "Nice family, you know, decent people. This is a terrible shame." He didn't know if John Connolly had done all these things. But it was a tough job back then - "People forget how tough".

Retired FBI agent John Morris, the prosecution's most valuable witness, looked terrified not tough as he recalled taking bribes during his tenure as Connolly's superior and the Mob's creature when he surely became the first and only drunken G-man ever to be driven home by Flemmi and Bulger. Morris fingered Connolly as crooked in 1998 during judicial hearings that exposed the links between the FBI and Boston's gangster establishment.

Granted immunity in exchange for that testimony, he also swore that he donated his $7,000 bribe to the church. "I got religion right after Bulger called me," Morris insisted, referring to the threatening call he received from the fugitive in 1995. "I got serious religion. I prayed every night." Hours after Bulger's call, Morris suffered a major heart attack.

The pale, thin-lipped bureaucrat - dubbed "a moral weakling" by the prosecution - wept as he testified for the first time at Connolly's trial and seemed likely to collapse again. As Morris sobbed a flicker of expression crossed Connolly's face. It could have been sympathy, embarrassment or disgust and it was gone in an instant.

During the 1998 hearings, Connolly took the Fifth Amendment. Outside the courtroom, however, he vented his anger daily. Running informants was "like a circus", he told reporters, "and if the circus is going to work you need to have a guy in there with the lions and tigers. That was me. I was no John Morris, back in the office with a number-two lead pencil. My job was to get in there with the lions and tigers. And I am no liar like Morris."

Bulger never gave Connolly a heart attack, never made him cry. If anything, Connolly was more at home with the gangsters he claimed to control than he was with FBI pencil-pushers.

In the witness box, however, Connolly's "lions and tigers" became grey-haired ambassadors from a sordid world. "Cadillac" Frank Salemme planted the car bomb in 1968 that blew off lawyer John Fitzgerald's leg.

Teaming up with Bulger and Flemmi in the mid-1980s, he took over the New England Mafia. "To quote the vernacular, I became the boss," Salemme, now 68, shaking uncontrollably and with a bullet still lodged in his stomach, told the court. "My role was to look over the family, over the flock, so to speak."

Salemme testified that Connolly tipped him off to a federal indictment, pocketed $10,000 in bribes and leaked the names of FBI informants to Bulger. It is the decline in Mafia not FBI standards, however, that worries Salemme. "It's too loose today," he complained, dismissing "the Mickey Mouse Mafia in Nevada. They don't make them like they used to." John Martorano, serving time for 20 murders between 1965 and 1982, echoed Salemme's sentiments. "I would never kill a woman," the still beefy but now bespectacled Martorano declared in a low growl: "Unless I had to. I mean, if she was there."

At least two women - Debra Davis and Deborah Hussey - were there. In 1981, Bulger's partner, Stephen Flemmi, killed his 26-year-old girlfriend, Debra Davis. Three years later, he murdered his then girlfriend, Deborah Hussey. The same age as Davis, Hussey was also the daughter of Flemmi's common-law wife.

Kevin Weeks, jailed since 1999 and bargaining for leniency, told police where to dig. In January 2000, three corpses were exhumed from a highway embankment in Dorchester: Arthur Barrett, a safecracker; John McIntyre, a gun runner who informed on Bulger after the 1984 Marita Ann fiasco in which Bulger reportedly double-crossed the IRA; and Deborah Hussey, whose fingers, toes and teeth had been removed.

"You heard Kevin Weeks," Tracy Miner reminded the jury in closing arguments for the defence. "He participated in five murders. He bragged that an insult in a bar is enough for him to kill someone. It was enough then and it's enough now." Calling just five defence witnesses to the prosecution's 27 (Connolly declined to testify), Miner argued that "thieves and liars" were paid for their testimony with immunity and reduced sentences, that "they hate John Connolly and when they hate they kill. This is payback, pure and simple". Above all, Miner insisted, the government needs a scapegoat, a "rogue agent" whose conviction will deflect attention from the endemic corruption in the FBI and other law enforcement agencies.

"Bulger and Flemmi took down the Mafia?" the owlish prosecutor John Durham responded incredulously. "Yet Salemme says that these 'top echelon informants' were giving the FBI garbage and getting gold." The reassuring vision of agents and mobsters co-operating to clean up Boston is as convincing as Bulger's vow to rat only on Italians and to protect Irish Southie against the flow of drugs from neighbouring, African-American Roxbury. "It was never about Southie," concludes Dick Lehr, author of several books on the FBI and the Mafia. "It was always about Bulger." The same might be said of Connolly, who reportedly craved mobster admiration even as he gloried in his role as Boston's Mafia slayer.

Probably no cleansing agent was equal to the foul task of eradicating either organised crime in the 1980s or the hardy breed of corruption that still flourishes in a city where Billy Bulger, hosting a St Patrick's Day cabaret breakfast, once sang a witty anthem to his brother, Whitey, and was joined in the chorus by William Weld, the US attorney general in Boston during much of Whitey's reign.

The New York Times also notes that current FBI chief Robert Mueller was the acting United States attorney in Boston during one period of Connolly's collaboration with Whitey Bulger.

"Corruption became a way of life in the Boston office of the FBI," Chris Lehr concludes, "It was a House of Horrors. That's what Mueller admitted when he came back here in 1998 and said that 'mistakes were made'."

In his instructions to the six-man, six-woman jury, Judge Tauro stressed that "the testimony of immunity witnesses must be weighed more critically . . . with caution and great care". The jury listened. After two days of deliberation, it rejected much of the testimony from convicted killers such as Martorano. But independent evidence - Connolly's forged letter to a federal judge in 1998 defaming a Boston detective; false statements to the FBI - proved compelling.

"I believe in the jury system," Connolly declared, as he left the courthouse last Friday. On Tuesday, the jury found John Connolly guilty on four of the five counts against him. The defendant, released on $200,000 bail, will be sentenced on August 7th. He faces a maximum of 45 years in prison, although sentencing guidelines call for less: 10 to 20. Prosecutors say they may bring additional charges against him. Connolly showed no emotion as the verdict was read.

"It's an important day for justice and a bad day for the FBI," said Gerard O'Neill, retired Boston Globe journalist who has followed Bulger's career since the 1960s. But longtime Connolly watchers are not celebrating.

They know that his story is not the whole story. And somewhere in the US or maybe in Ireland, Bulger must be asking himself if his old friend Connolly is going to start talking again.