Washington (CNN) -- Two veteran senators complained Wednesday that military officials might have been slow to react to an alleged prostitution scandal in Colombia and have not been forthcoming with Congress in reporting what happened.
The incident this month before President Barack Obama's trip to the Summit of the Americas in Cartagena involved Secret Service and U.S. military members who allegedly consorted with prostitutes.
Twenty-four people have been linked to the scandal: 12 from the Secret Service and 12 from the military.
Nine of the Secret Service members have resigned or are being forced out, and three others were cleared of serious misconduct, while a separate military investigation has yet to announce any measures against the members allegedly involved.
After receiving their first briefing on the investigation from military officials, Senate Armed Services Committee members Carl Levin of Michigan and John McCain of Arizona expressed dissatisfaction Wednesday with the military's response.
"It was a waste of time because they had no information," said McCain, the panel's ranking Republican. "They told us the mechanics of what's happening, but certainly no information about the issue that we and all Americans are concerned about. And that's not behavior, that is whether there was a breach of national security associated with this situation."
Levin, the committee's Democratic chairman, said that some of the military personnel involved violated their curfew but were allowed to stay on the mission, where their role was protecting the president.
"That may have been the right decision, but it nonetheless raises an interesting question as to whether once there was information that six of the 12 that have had some issues raised with them and that are under suspicion -- once that information was available up the chain of command, whether that was an appropriate decision to let them continue on the mission, given the seriousness of the mission," he said.
Levin described the military's briefing as "sketchy."
"They were reluctant to provide the data," he said, noting the investigation is continuing and the officials who provided the briefing "don't have the information ... really in any detail because they're not doing the investigation."
He said he expected that the military investigation would be completed within 10 days or so, and that the committee would get another briefing around May 7.
A congressional source tells CNN the House Oversight and Government Reform Committee, chaired by Darrell Issa, has been in touch with Greg Stokes, a member of the Secret Service being forced out in the wake of the scandal.
This source spoke on condition of anonymity in order to discuss private committee conversations.
The source said no decision had been made on whether Stokes would be called as a witness when the committee is ready to hold public hearings.
A spokesman for the U.S. Southern Command, which is overseeing the military investigation, said the military members who were under suspicion were restricted to their hotel rooms while not performing their duties in Colombia.
"U.S. military leaders in Cartagena, in close coordination with the U.S. Secret Service lead there, decided that, given their skills, experience and expertise, moving U.S. military personnel would've been disruptive to the mission," said the spokesman, Jose Ruiz. "The military personnel under investigation remained to perform their assigned duties but were otherwise restricted to quarters."
Earlier Wednesday, Homeland Security Secretary Janet Napolitano told the Senate Judiciary Committee that Secret Service Director Mark Sullivan has the full confidence of the president after the scandal.
Napolitano promised a full investigation to ensure that "this kind of conduct doesn't happen again."
"There was nothing in the record to suggest that this behavior would happen, and it really was, I think, just a huge disappointment to the men and women of the Secret Service, to begin with," she told the first congressional hearing to address the incident earlier this month.
Asked whether the misconduct was a systemic problem at the Secret Service, Napolitano replied: "If it is, that would really be a surprise to me."
The scandal embarrassed the nearly 150-year-old agency and raised questions about a possible security breach before Obama's trip to Colombia.
Secret Service spokesman Edwin Donovan said Wednesday that the agency's inquiry into the controversy continues in Colombia.
"We still have folks on the ground in Cartagena," Donovan said, adding that "interviews and corroborative interviews continue."
Obama commented Tuesday on the scandal in an interview with NBC's "Late Night With Jimmy Fallon," saying "99.9%" of Secret Service agents do great work and put their lives on the line.
"So, a couple of knuckleheads shouldn't detract from what they do, but what these guys were thinking, I don't know," Obama said. "That's why they're not there anymore."
His spokesman, White House press secretary Jay Carney, told reporters Wednesday that Obama was "angry" about the "inappropriate behavior, behavior that is not acceptable for people who work for the U.S. government or representing the American people abroad."
Napolitano told the Senate Judiciary Committee that Obama's security was not jeopardized by the heavy drinking and consorting with prostitutes alleged to have occurred prior to his arrival in Colombia.
"There was no risk to the president," she said.
No evidence suggests that any misconduct in Colombia reflected normal behavior by Secret Service agents, Napolitano added.
"To my knowledge, there have been no similar-type incidents reported to the Office of Professional Responsibility," she said.
Referring to an argument that the Secret Service agents involved should be spared harsh penalties because others engaged in similar behavior, Napolitano was unpersuaded.
"First of all, not everybody else is doing it," she said, adding that the behavior involved was unacceptable.
According to sources, the alleged prostitutes -- the youngest of whom were in their early 20s -- signed in at Hotel Caribe in Cartagena, where Secret Service members apparently stayed. One of these women allegedly was later involved in a dispute over how much she was to have been paid for the night, which brought the incident to light.
That woman has been identified as Dania Suarez, whose neighbors described her as a 24-year-old single mother who studies English. Suarez hasn't been seen in her neighborhood since the controversy erupted, though a visitor took suitcases from her house recently, they said.
While soliciting prostitution is in most cases legal for adults in Colombia, military law bars service members from patronizing prostitutes, engaging in conduct unbecoming an officer or, for enlisted personnel, conduct "prejudicial to good order and discipline." It is also considered a breach of the Secret Service's conduct code, government sources said.
On Tuesday, the agency announced that two more members resigned over the scandal, while another member was being forced out and two more were cleared of serious misconduct.
The latest resignations brought to nine the number who have resigned or are being forced out because of the controversy, with three others cleared of the most serious allegations but still facing possible administrative discipline.
Sen. Chuck Grassley, the top Republican on the Senate Judiciary Committee, said Tuesday that he wants an outside investigation to determine whether any White House staff members may have engaged in inappropriate behavior in Colombia.
At Wednesday's hearing by the panel, Grassley acknowledged that the inspector general at the Department of Homeland Security was involved in the investigation, which Napolitano said was part of an agreement involving her department, the Secret Service and the inspector general.
Carney said this week that White House Counsel Kathryn Ruemmler conducted an internal review over the weekend and found no wrongdoing by members of the Obama advance team in Colombia ahead of the president's trip.
Grassley is demanding that, in addition to an independent investigation of White House staffers, the White House counsel make public details of her internal inquiry.
On Monday night, Grassley sent a letter to Ruemmler, asking about how the inquiry was conducted and how the conclusion was reached. Asked Tuesday about Grassley's letter, Carney said he had not seen it.
In his letter, Grassley noted that he had asked Sullivan, the Secret Service director, whether any White House advance staffers had been involved, but he hadn't received an answer by Monday.
Grassley asked for answers to 14 questions, including details of how the White House review was conducted, whether any White House staffers had "overnight guests" and whether any additional room charges were incurred.
However, Senate Homeland Security Chairman Joe Lieberman of Connecticut, an independent who caucuses with Democrats but often differs with them, said he was satisfied with the White House counsel's inquiry.
"If the White House counsel says nobody from the White House staff was involved in this behavior, then I'm prepared to accept that," Lieberman said. "And if we find out that isn't true, then we're going to find out about it, and it's going to be a big mistake by the White House, but I have no reason to doubt what they say."
Lieberman said he intends to hold a committee hearing focusing on potential misconduct inside the Secret Service beyond what happened in Colombia.
Since the scandal broke, several whistle-blowers have called his committee with what he called "credible" reports of other incidents similar to those alleged to have taken place in Colombia, Lieberman said. He would not provide details.
After he spoke, however, Senate Homeland Security Committee spokeswoman Leslie Phillips said Lieberman had misspoken. The committee has received a call from just one person who claimed to have information on possible misconduct, but committee staff members have yet to talk to that person to determine whether that information is relevant, she said.
Issa, the House Oversight Committee chairman, said Tuesday that his committee has heard allegations of similar misconduct by Secret Service agents dating back years. Like Lieberman, the Republican offered no specifics.
Issa and the panel's ranking Democrat, Rep. Elijah Cummings of Maryland, sent a letter to Defense Secretary Leon Panetta requesting details of the military investigation by May 8. Last week, the two sent a similar letter to the Secret Service last week.
Panetta said Tuesday that he has "no tolerance" for the kind of behavior alleged to have taken place in Cartagena, noting that Marines involved last year in an altercation with prostitutes in Brazil were punished.
Panetta was asked about the December incident at a news conference in Brazil, according to a TV pool report.
Three Marines and a State Department employee were involved in an altercation over payment with dancers and prostitutes from a Brazilian club. One woman allegedly started a fight inside a Marine's vehicle and was injured when she was kicked out of the vehicle and tried to get back in.
On Monday, officials said a member of the U.S. military assigned to the White House Communications Agency was under investigation in connection with alleged misconduct in Colombia, bringing to 12 the total number of military personnel being reviewed.
One Defense Department official said the military member admitted to his leadership that he had been involved in misconduct "of some kind" while in Colombia.
The agency is a non-White House office that provides the president with secure communications while he travels. It is staffed by members of the military who report through the Defense Information Systems Agency.
While the 11 other military members are being investigated by the U.S. Southern Command, it was unclear who would investigate the White House Communications Agency staffer, who has been relieved of his duty with the agency and reassigned to the Military District of Washington, Pentagon spokesman Capt. John Kirby said.
CNN's Dana Bash, Dan Lothian, Deirdre Walsh, Mike Mount and Barbara Starr contributed to this report.