John J. Connolly was hundreds of miles away in 1982 when gambling executive John Callahan's bullet-riddled body was discovered in the trunk of his Cadillac at Miami's airport.

MIAMI — John J. Connolly was hundreds of miles away in 1982 when gambling executive John Callahan's bullet-riddled body was discovered in the trunk of his Cadillac at Miami's airport.

The admitted shooter says he never met Connolly, the disgraced ex-FBI man at the heart of the agency's sordid dealings with Boston's Winter Hill Gang.

Yet Connolly will stand trial on murder and conspiracy charges this month as if he had pulled the trigger himself, because prosecutors say he secretly gave information that was crucial in setting up the hit. Jury selection is to begin Monday in a trial that figures to rehash some of the ugliest episodes in the Boston FBI's handling of the gang, once led by James "Whitey" Bulger and convicted killer Stephen "The Rifleman" Flemmi.

For years, both were top FBI informants on rival Italian mobsters. Connolly was their handler — and Connolly made sure they were shielded from prosecution for murder and many other crimes, a service for which he was eventually sent to federal prison on a racketeering conviction.

A congressional investigation concluded in 2003 that the FBI's relationship with Bulger and his cohorts "must be considered one of the greatest failures in the history of federal law enforcement." The scandal spawned several books and was the template for the 2006 Martin Scorcese film "The Departed," with Matt Damon playing a crooked Connolly-like law enforcement officer and Jack Nicholson as the Bulger-esque Irish-American mobster.

And it led former Attorney General Janet Reno in 2001 — one of her last acts in office — to install reforms on FBI use of criminals as informants, including better monitoring and accountability.

The Callahan slaying is part of that history, detailed in numerous court documents, interviews and investigative reports.

Callahan was president of World Jai-Alai, a Miami fronton, or facility, for the sport in which gamblers bet on players who sling a small ball against a wall using wicker baskets. World Jai-Alai was purchased in the late 1970s by Roger Wheeler, a businessman from Tulsa, Okla., who liked the fact that former Boston FBI agent Paul Rico was part of the security team.

Soon, however, Wheeler suspected that Callahan was skimming profits from World Jai-Alai for the Winter Hill Gang. He fired Callahan and ordered an audit.

On May 27, 1981, Wheeler was shot between the eyes at a Tulsa country club by hit man John V. Martorano, who has admitted in court to 20 murders.

Callahan was targeted next because Bulger and Flemmi feared he would finger them for Wheeler's killing. Martorano pleaded guilty in 2001 to shooting Callahan and, with the help of an associate, stuffing his body into the trunk of Callahan's silver Cadillac.

Authorities found the car at Miami International Airport, with a dime placed on Callahan's body as a warning against potential informants not to "drop a dime" or rat out associates.

Rico, Connolly's former FBI colleague, was eventually charged in Wheeler's murder, but he died in 2004 before going to trial. A little over a year later, Connolly was indicted by a Miami-Dade County grand jury in Callahan's killing. A conviction means a life prison sentence.

Connolly, 68, is already serving a 10-year federal prison stretch for racketeering and other charges from his associations with Bulger and his gang, including tipping his former informant off about an impending 1995 indictment.

Bulger — the brother of William Bulger, the former state Senate president who resigned as president of the University of Massachusetts in 2003 — fled before he could be arrested and remains a fugitive, a fixture on the FBI's "Ten Most Wanted" list.

The FBI has checked out hundreds of tips regarding his whereabouts, including Spain, Italy, Portugal, Mexico, Great Britain and Germany. Last week, the agency marked his 79th birthday by doubling the reward for a tip leading to his capture to $2 million.

The federal jury that convicted Connolly in 2002 rejected evidence of his involvement in the Callahan killing, although the charge then was obstruction of justice. And Connolly's lawyer, Manuel Casabielle, said little new has surfaced in the years since.

"The reason you haven't seen much connecting John to the Callahan murder is because there isn't much. It isn't there," Casabielle said. "Most of what they have comes from two people who have admitted at least 40 murders between them."

But prosecutor Michael Von Zamft said the state is confident in its case, even with key witnesses of questionable repute.

"I've tried lots of cases where jurors have not liked some witnesses personally. But that does not make them not believable," he said.

Martorano, the self-described hit man, is among the star witnesses, along with Flemmi and other Winter Hill Gang figures. The gist of Martorano's testimony, according to court documents, will be that it was Bulger who told him that Connolly was involved setting up the Callahan slaying.

Martorano served 12 years in prison for murder and dozens of other crimes under a plea agreement requiring him to testify in numerous cases, including Connolly's.

During his FBI career, Connolly won numerous commendations and awards and is credited with making key arrests of Italian Mafia chieftains in Boston. His supporters have unearthed evidence indicating that senior Justice Department and FBI officials tolerated the criminal exploits of Bulger and Flemmi because of their value as mob informants.

Connolly's former Boston attorney, Edward Lonergan, has known Connolly since 1961 and called him "the strongest man I know."

"He was and is a credit to the FBI at its best. But the FBI is not always at its best," Lonergan said. "I am now convinced that he is a most unfortunate victim of a human and flawed system."