United States Attorney John H. Durham has kept such a low profile while handling some of the country's most infamous criminal investigations that he once made New Republic magazine's list of Washington's "most powerful, least famous people."

Durham "made his bones," as he would say, prosecuting mobsters, corrupt federal agents and former Connecticut Gov. John G. Rowland. He's been tapped by United States attorneys general to investigate topics as touchy as alleged torture and coverups during CIA investigations.

The 67-year-old Groton resident, nominated as Connecticut's top federal prosecutor by President Donald Trump and endorsed by Republicans and Democrats alike, has confined most of his public speaking to within the four walls of federal courtrooms.

As the state's U.S. attorney, Durham takes on administration duties over the state's 68 federal prosecutors and 50-odd staff members who work in courthouses in Bridgeport, New Haven and Hartford. He plans to continue trying cases and has a murder trial coming up later this year.

A week after being sworn in, Durham, perhaps realizing that his new role calls for higher visibility, delivered a lecture at the University of St. Joseph in West Hartford, a formerly all-female school that is going all co-ed this year and ratcheting up its criminal justice program.

For about an hour this past Monday, he regaled an audience with an insider's view of the widely publicized investigations that brought down mobsters James "Whitey" Bulger, Stephen "The Rifleman" Flemmi and their corrupted FBI handler, Special Agent John Connolly Jr. It was a case that extended into Connecticut, where gambling venues for the sport jai alai were infiltrated by Bulger's Winter Hill Gang.

Bodies had been piling up in Boston throughout the 1970s and 1980s, and by 1999, after it became clear that members of Boston's FBI bureau had been compromised by the Irish and Italian mafia, Attorney General Janet Reno and FBI Director Louis Freeh called on Durham and others from Connecticut to help.

"It was quite the scandal that was going up there in Boston," Durham told the audience at St. Joseph's. "We were asked to go up there because we had some familiarity with the New England LCN (La Cosa Nostra) and knew some of the judges and the investigators and so forth. So the Justice Task Force was formed to investigate corruption involving the FBI and others."

Durham's longtime partner in crime-fighting, Deputy Chief State's Attorney Leonard C. Boyle, introduced the U.S. attorney to the university gathering as the person members of the Connecticut bar call when stumped by a legal question. Boyle said Durham has "an extreme work ethic" and is working all the time, whether in the office or at home.

Boyle said Durham has an uncanny ability to identify the smallest of facts in a case "and weave it together into a tapestry of detail," but joked that Durham's skill does not extend to his attire. Durham has a tendency to mismatch his suit jackets and trousers, Boyle said, and it's only when he's standing in a courtroom, addressing a jury, "when he realizes that particular day he wore the gray striped jacket with the Navy-blue pants."

Boyle seemed as amazed as anyone that his friend had agreed to the speaking engagement, since Durham is "notoriously shy about speaking about himself or what he does."

The University of St. Joseph's affiliation with the Catholic church may have helped.

"Other than an overwhelming commitment to the cause of justice, the two great devotions of John's life are his Catholic faith and his family," Boyle said. The Courant has reported several times that Durham also is an avid Red Sox fan.

Durham and his wife, Susan, have four sons — two of them prosecutors — and eight grandchildren.

Durham's lecture, delivered along with a PowerPoint presentation entitled "The Use of Informants: A Cautionary Tale," contained hints of his own restrained approach to investigations. Using criminals to gather information about other criminals is a necessity in cases where the average citizen is justifiably scared but, at best, is a "double-edged sword," Durham said.

In the Boston case, Bulger and Flemmi, both working as "Top Echelon" informants for the FBI, corrupted their handlers, and during the course of his trial, Flemmi asserted he had been told by FBI supervisor John Morris, "You can commit any crime as long as you don't 'clip' anybody," Durham said.

"The reality was that both Bulger and Flemmi were notorious, really bad actors in Boston when they were recruited by the FBI as informants in Boston," he said.

Durham said the FBI had plenty of regulations in place when the two men were signed up as informants in the late 1960s, including that they could not commit crimes, but the mobsters acted as if "they had the keys to the kingdom," bribing their handlers and using leaked information to further their control of narcotics trafficking, loan sharking and extortion in the city. The men also were responsible for about 20 murders, according to news reports.

In the aftermath of the case, regulations were put into place that require prosecutors to sign off on the use of informants.

Informants should be used as an investigative starting point, Durham said, and the information they provide should be corroborated through other means or used to convince a judge to authorize wiretaps in which a defendant's own words (during secretly recorded telephone conversations) can be used to build a case against them.

Durham's Boston team, including Boyle and FBI agents from outside of the city, worked the case for about a year before indicting Flemmi and Connolly, who had retired by then from the FBI, for racketeering and obstruction of justice. Bulger, at the time, was a fugitive from justice.

Flemmi pleaded guilty to racketeering and 10 murders and is serving a life sentence.

Connolly, nicknamed, "Zip," went to trial in 2002, and Durham, who prosecuted, said it was a "unique" proceeding in which the defendant was allowed to sit with his wife in the courtroom gallery. The prosecution team had made "the very difficult decision," after consulting with the U.S. attorney general and victim's families, to use as a witness John Martarano, a mob hitman who had confessed to killing 20 people.

The media followed the case closely, and while Durham saved his comment for the courtroom, he collected some of the colorful headlines generated during the Connolly trial and used them in his PowerPoint presentation. One described the once-defiant FBI agent "cowering" in the courtroom, and the Boston Herald's headline, after Connolly was convicted, said simply, "Zip Zapped."

Connolly served 10 years in that case and later was charged with providing information to Flemmi and Bulger that led to the 1982 murder in Miami of jai alai executive John Callahan. Now 77, Connolly is serving a 40-year prison sentence in Florida.

Bulger, captured in 2011 after 16 years as a fugitive and tried two years later, is serving a life sentence.

Bulger's Winter Hill Gang was decimated as a result of the federal prosecutions, Durham said, and La Cosa Nostra is "nothing like it was."

There's still plenty of work for federal authorities, though. Durham said one of the consequences of breaking up organized crime operations is that the concentration of criminal activity becomes much more diffuse.

Back in Connecticut, Durham's office prosecutes some of the state's most violent crimes and high-level narcotics cases, financial fraud and public corruption, as well as cases involving national security.

k.florin@theday.com