WASHINGTON - They are known for their shiny sunglasses, dark suits, and stern gazes.
Secret Service agents, the men and women who protect U.S. leaders, are as much a part of the American political tableau as the presidents, cabinet officials, and candidates they shadow and protect.
But, unlike their high-profile charges, they are not supposed to make news.
The suspension of 11 agents this weekend after alleged misconduct involving prostitutes in Colombia brought unwelcome headlines and attention to the agency's culture.
One critic said the incident reflected a systemic breakdown of standards and practices among overworked agents that could leave a president vulnerable to an attack.
An investigation will show whether the event, which overshadowed President Barack Obama's meetings with Latin American leaders in Cartagena, Colombia, was an unfortunate anomaly or a sign of an agency-wide problem.
Either way, it shed light on the human frailties and working conditions of a group expected to perform discreet and self-sacrificing services for U.S. leaders.
People familiar with the Secret Service described long work hours on stressful presidential trips, some of which are scheduled at the last minute.
Agents often meet at hotel bars at the end of the day on such trips to drink and unwind. Those who are not traveling with the president sometimes hold "wheels-up" parties after Air Force One has lifted off for Washington or another destination.
On Thursday, some U.S. agents brought a number of prostitutes back to a beachfront hotel in Cartagena near where Obama was due to stay the following day, according to a local police source, sparking a weekend of scandal.
"We've heard about these wheel-up parties when the president leaves," said congressman Darrell Issa, speaking on CBS' "Face the Nation" program.
"Well, this was a pre-wheel-down. So the question is, is the whole organization in need of some soul-searching, some changes ... before the president, the vice president, members of the cabinet are in danger?"
Ralph Basham, a former director of the agency who is now a principal with Command Consulting Group, said the incident was a rare mishap for an agency that prides itself on its professionalism.
"I do not believe that there is a systemic problem in the Secret Service because if there were, this wouldn't be such a huge story," he told Reuters in an interview.
"This is really an abnormality."
"Willing to take a bullet"
David Gergen, a political analyst who worked for four presidents including Ronald Reagan, who survived an assassination attempt thanks to Secret Service protection, said occasional incidents such as the one in Colombia were not out of character given the masculinity of many in the profession.
Overall, he said, the agents were brave, outstanding people.
"These are guys who are willing to take a bullet to save a president. I've seen them do that," Gergen said. "My hope is people keep it in perspective."
One prominent critic was less forgiving, saying the connection to prostitutes should end the careers of the agents involved.
"The fact that they were engaged in this conduct, you know, compromises the agents," said Ronald Kessler, author of "In the President's Secret Service: Behind the Scenes With Agents in the Line of Fire and the Presidents They Protect."
"The prostitutes could have blackmailed them, could have been involved with terrorists, drug cartel people, or foreign intelligence services," he said. "Any foreign intelligence service would love to get a Secret Service agent in their pocket."
Kessler said the events in Colombia were illustrative of a general slide of Secret Service standards. He cited the admittance of uninvited guests to a White House holiday party early in Obama's tenure as further evidence of lax behavior.
The Secret Service stressed that Obama's safety was never in question and rejected Kessler's claims of a wider problem.
"We have hundreds of personnel that travel around the world every day that conduct thousands of security advances, thousands of events, and we don't have incidents like this that occur,' said Ed Donovan, an agency spokesman. "It's an anomaly."
Obama, speaking at the end of the summit, said he, too, would withhold judgment until all of the facts were established.
"These men and women perform extraordinary service on a day- to-day basis protecting me, my family, U.S. officials. They do very hard work under very stressful circumstances and almost invariably do an outstanding job," he told reporters.
Even so, Obama said he would be "angry" if the allegations about the agents in Colombia proved true.
"I'll wait until the full investigation is completed before I pass final judgment," he said