(WASHINGTON) — The 11 Secret Service agents accused of soliciting prostitutes and drinking excessively while on assignment in Colombia will be forced to take lie detector tests to determine exactly what happened, ABC News has learned.

The alleged misconduct in Cartagena, Colombia, came before President Obama arrived there last Friday to attend the Summit of the Americas.

Sen. Susan Collins, R-Maine, said in a statement Tuesday that the scandal involved “twenty or twenty-one women foreign nationals,” about nine of whom were allegedly involved with Marines.  Collins’ knowledge of the incident came from a briefing she had with Secret Service Director Mark Sullivan.

Sources tell ABC News that many of the suspected prostitutes have been identified and will be interviewed.

Investigators will also be on the ground in Cartagena Wednesday morning, canvassing night clubs, interviewing hotel employees and collecting hotel surveillance video.

video platform video management video solutions video player

Copyright 2012 ABC News Radio