The director of the Secret Service will be called before a Senate committee May 23 to provide details about the investigation into the Colombia prostitution scandal that has resulted in the dismissal of nine agency employees.

Director Mark Sullivan has not spoken publicly on the misconduct that took place last month in Cartagena, Colombia, where a dozen agents were implicated in a night of carousing two days before President Obama arrived for an international summit.

Sen. Joseph I. Lieberman (I-Conn.), chairman of the Homeland Security and Government Affairs Committee, announced the hearing Sunday during an appearance on CNN’s “State of the Union.” Charles K. Edwards, acting inspector general of the Department of Homeland Security, who is conducting an independent investigation, also will be called to testify, Lieberman said.

The senator said he would seek to determine whether there were warning signs that the scandal could occur and what steps Sullivan is taking to ensure that similar misconduct will not happen again.

“This is really a heartbreaking incident, and really a dangerous incident, and we really have got to make sure it never does happen again,” Lieberman said on the show.

A dozen Secret Service employees were implicated in a night of partying April 11 that included heavy drinking, visits to a strip club and payments to prostitutes. In the wake of the scandal, the agency dismissed nine employees and has subjected three to demotion or disciplinary action.

Sullivan also imposed stricter rules for foreign trips, including more higher-ranking chaperones and a ban on foreign nationals in the hotel rooms of Secret Service employees. The agency also has begun mandatory training sessions to explain the rules to agents and officers.

Some current and former agents have said that the Secret Service had for years tolerated heavy drinking and liaisons between agents and foreign women during road trips. However, Rep. Peter T. King (R-N.Y.), chairman of the House Committee on Homeland Security, said on CNN that he does not believe the behavior was part of the agency’s culture.

“I believe this was the exception. I don’t believe it was tolerated,” he said.

King added that his office received a call from a lawyer representing Dania Suarez, a Colombian woman who has claimed to be at the center of the scandal. Suarez has said that an agent refused to pay her after she spent the night in his room, causing a disturbance in the hallway of the Hotel Caribe that led to the scandal becoming public.

King said that the lawyer offered to meet with him in Washington but that he declined the invitation.

“We’re not going to do that. I think that would just add to a circus atmosphere,” King said. “This is a very, very outstanding agency, the Secret Service. We have to not tear down their reputation while getting at the truth of what happened.”