From Dan Lothian,
CNN White House Correspondent
updated 8:01 AM EDT, Sat April 14, 2012
Cartagena, Colombia (CNN)
-- Twelve Secret Service agents sent to Colombia ahead of President Barack Obama were relieved of duty and returned home amid allegations of misconduct that involved prostitution, the man who tipped news agencies to the investigation told CNN Saturday.
The incident in Cartagena -- one of two security issues that occurred Friday -- overshadowed the start of the sixth Summit of the Americas, where the president was to focus on trade, energy and regional security with 33 of the hemisphere's 35 leaders.
"One of the agents did not pay one of the prostitutes, and she complained to the police," said Ronald Kessler, a former Washington Post reporter and author of "In the President's Secret Service: Behind the Scenes With Agents in the Line of Fire and the Presidents They Protect."
The Washington Post, which was the first to report the story, said it was alerted to the investigation by Kessler.