The agency's investigation has included interviews of agents and hotel staff. Rep. Peter King, chairman of the House Homeland Security Committee, said this week that investigators in Colombia have not been able to interview the women.
The affair has also prompted a military investigation of the service members, including six members of the Army, two Navy Explosive Ordinance Disposal technicians, two Marine dog handlers and an Air Force airman.
An Air Force colonel and a military lawyer were also dispatched to Colombia this week. Under the Uniform Code of Military Justice, patronizing prostitutes is a crime for military personnel. It is referred to as "compelling, inducing, enticing or procuring a person to have sex in exchange for money; or receiving money for arranged sex."
Officials from U.S. Southern Command, which organized the military role for the security operation, have not provided details of its probe beyond saying that at least some of the military members violated curfew and may have been involved in "inappropriate conduct."
White House press secretary Jay Carney has said it is "preposterous to politicize" the issue, responding to criticism from Alabama Sen. Jeff Sessions and Palin, who have said the allegations reflect poor management of the government under Obama.
Palin described the affair Thursday as a "symptom of government run amok."
"It's like, who's minding the store around here?" Palin said.
Associated Press writers Eileen Sullivan, Laurie Kellman, Robert Burns, Larry Margasak, and Julie Pace in Washington, Nomaan Merchant in Dallas and Frank Bajak in Cartagena, Colombia, contributed to this report.
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