The prostitution scandal in Colombia involved about 11 U.S. Secret Service employees and "twenty or twenty-one women foreign nationals were brought to the hotel," about nine of whom were allegedly involved with Marines, Sen. Susan Collins, R-Maine, said in a paper statement today.

Collins' knowledge of the incident comes from a 30-minute briefing she said she received Monday night from Secret Service Director Mark Sullivan about the accusations of  misconduct in Cartagena, Colombia, before President Obama arrived there Friday to attend a conference.

"Director Sullivan is rightly appalled by the agents' actions and is pursuing a vigorous internal investigation," Collins said.  "He ordered all the agents to return to Washington immediately, and all have been interviewed."

Collins is the ranking member of the Homeland Security & Governmental Affairs Committee, which has jurisdiction over the Department of Homeland Security and is the Senate's chief oversight committee. She said she raised the following questions at the briefing:

 "1 . Who were these women?  Could they have been members of groups hostile to the United States?  Could they have planted bugs, disabled weapons, or in any others jeopardized security of the president or our country?

 "2 . Is there any evidence of previous misconduct by these or any other agents on other missions?

"3. Given the number of agents involve, does this indicate a problem with the culture of the Secret Service?"

She said Sullivan has promised to keep her updated on developments.

"I am confident that he will fully investigate these troubling issues as well as pursue appropriate action against the agents should the allegations prove true," Collins said in the statement.