Correction: Earlier versions of this article incorrectly said nine Secret Service employees had been “indicted” in the scandal. The correct term is “implicated.”

Mark Sullivan, director of the Secret Service, is weathering the second scandal on his watch. In 2009, he testified before the House Homeland Security Committee on the gate-crashers at a White House State Dinner. (Brendan Hoffman/BLOOMBERG)

As the salacious details of the Secret Service sex scandal have cast an intensely private agency into the spotlight, the man at its helm has managed the crisis largely out of public view, a low-profile response that associates say belies his disgust with the conduct of his subordinates.

Colleagues describe Mark Sullivan, 58, director of the service since 2006, as a soft-spoken and even-tempered leader from an Irish Catholic family who has joked that he chose a law enforcement career over an earlier goal of entering the priesthood. Though he has not yet offered a public defense, those who have spoken with Sullivan say he is deeply disturbed by the reports of heavy drinking, visits to strip clubs and payments to prostitutes just two nights before President Obama arrived in Cartagena, Colombia, two weeks ago.

It is the second major embarrassment for the agency on Sullivan’s watch, coming more than two years after a pair of uninvited guests talked their way past Secret Service officers at the White House to enter a state dinner and mingle with Obama and Vice President Biden. But if that error represented a procedural failure, the Cartagena scandal has exposed an apparent laxness of culture and accountability within the agency that could prove much more difficult for Sullivan to fix — if he is given the chance.

Ralph Basham, who ran the Secret Service from 2003 to 2006 and recommended to President George W. Bush that Sullivan succeed him, said current and former agents are “ashamed of what these people did.”

“The whole college spring break mentality these folks were engaged in — that’s not the Secret Service that I know,” said Basham, who remains supportive of Sullivan.

The director has moved swiftly to mete out punishment, severing ties with nine of the employees implicated in the scandal while clearing three others of serious misconduct. In doing so, Sullivan appears to have maintained support from the White House and Capitol Hill.

Several lawmakers praised him for launching the internal investigation and compared him favorably with Martha N. Johnson, who abruptly quit three weeks ago as head of the General Services Administration after a watchdog’s report unearthed lavish spending at a Las Vegas conference.

At a Senate committee hearing Wednesday, Homeland Security Secretary Janet Napolitano declared that Sullivan “has the president’s and my full confidence as this investigation proceeds.”

Rep. Peter T. King (R-N.Y.), chairman of the House Committee on Homeland Security, said the director “is not a screamer, but he was as angry as I ever heard him at the agents who put the agency and the president in this position.”

A decorated career

The two public humiliations in the past three years have stained an otherwise decorated ­three-decade rise for Sullivan, who grew up in the Boston suburbs as the eldest of six children. Tall and lean, Sullivan is an avid runner who played hockey at St. Anselm College and remains a passionate Boston sports fan, friends said. He and his wife, Laurie, have three children.

Sullivan joined the service in 1983 and was assigned to the Detroit field office, where he quickly made a name for himself as a skilled investigator of financial crimes.

James Huse Jr., who oversaw the Detroit bureau in the late 1980s, recalls the case of a technology company that had defrauded the government out of grant money. Sullivan led his team into a warehouse where files were strewn across the floor and painstakingly reconstructed the records, ultimately leading to a conviction.

“It was a huge job, but he has always been somebody who could take on complex, major projects,” said Huse, who is retired but keeps in touch with Sullivan.

He quickly rose through the ranks, spending time on the presidential protective detail and overseeing the Columbus, Ohio, field office before joining the ranks of upper management in 2000, when he was promoted to be deputy assistant director of the Office of Protective Operations.

Things changed for the agency in the wake of the Sept. 11, 2001, terrorist attacks. Security details were beefed up for a greater number of dignitaries. Between 2002 and last year, the agency’s budget nearly doubled, to $1.5 billion, covering 3,500 agents and 1,400 uniformed officers.

In the past fiscal year, the service provided protection to U.S. dignitaries on more than 5,600 domestic and nearly 400 international trips. The agency also operates 142 domestic and 23 international investigative field offices.

“Protecting the president 10 years ago was very different than now,” said Jessica Herrera-Flanigan, a former general counsel for the House Committee on Homeland Security. She still works closely with the service as a legislative director for a private-sector consulting firm.

Sullivan has “done a good job making sure the Secret Service is effectively looking at issues like that without wasting money,” she added.

‘Rife with problems’

The culture of the agency was another matter. In 2002, a U.S. News & World Report investigation found a Secret Service “rife with problems and resistant to oversight and correction.”

The magazine cited alcohol abuse, criminal offenses and extramarital affairs between agents and White House employees. Male officers had viewed pornography on White House satellite channels in the mansion, clicking three times into each other’s earpieces to signal when female colleagues were approaching. Supervisors in two field offices had authorized professional strippers at office parties.

The allegations were “thoroughly looked at by the service, but I can’t tell you the exact outcome,” said Basham, who took over the agency in 2003. “Quite frankly, the Bush administration at the time was looking for a change in direction, but it was not anything specifically in all that that they were concerned about.”

Still, in the wake of the Cartagena scandal, some of the dismissed agents contend privately that management tolerated similar rowdiness on other foreign trips. That two supervisors were implicated in the partying has added to the questions of accountability.

Joseph Hagin, who served as White House deputy chief of staff for operations from 2001 to 2008, acknowledged that the service’s proximity to the White House can sometimes make agents “feel empowered, and that attitude can be dangerous.”

But overall, he said, the service has performed professionally amid the heightened anxiety after Sept. 11.

Being an agent “seems very exciting, but it is extremely hard work, a difficult travel schedule, a lot of standing around and waiting,” said Hagin, who now operates the Command Consulting Group. That company provides security and intelligence consulting, through which Hagin maintains ties to the service.

“I felt it was my job, especially after 9/11, to keep a close eye on the readiness of all the systems around the presidency,” Hagin said. “One thing I never worried about was those guys.”

The gate-crashers

Basham installed Sullivan as head of human resources and training in 2003, then promoted him to become deputy director, the No. 2 job at the agency. Sullivan succeeded him in 2006.

Sullivan passed his first big test — the 2008 election cycle, during which the service protected the first major African American and female presidential candidates, under increased threat levels — without incident.

In late 2009, however, the White House gate-crashers escapade made unlikely celebrities out of Tareq and Michaele Salahi and forced Sullivan to submit to a round of mea culpas on Capitol Hill. He fired three officers and emerged with his reputation mostly intact.

Lawmakers said Sullivan salvaged his reputation — and in some ways burnished it — with his forthright testimony in the ensuing oversight hearings on Capitol Hill, which some legislators privately dubbed the “Mark Sullivan self-preservation tour.”

“A mistake was made,” he said at the time. “In our line of work, we cannot afford even one mistake. I fully acknowledge that the proper procedures were not followed. . . . This is our fault, and our fault alone.”

Even before the Cartagena incident, this year promised to be challenging for the service, with the 2012 campaign bringing an intense travel schedule. On April 7, a few days before the Cartagena scandal broke, Keith Prewitt, a 29-year veteran who had been Sullivan’s top deputy since 2008, left the agency for the private sector, leaving a void of institutional knowledge that Sullivan’s potential departure would only compound.

In a letter to staff members on April 16, Sullivan wrote that the “overwhelming majority” of Secret Service personnel meet the agency’s high standard.

“I am extraordinarily proud of you for that and I am honored to serve with you,” he wrote. But, he added, it is because of the “vital aspects of our charter that an ‘overwhelming majority’ is insufficient.”

Staff writers Ed O’Keefe and Del Quentin Wilber contributed to this report.