(CNN) -- Three more Secret Service employees have "chosen to resign" from the agency in the wake of a prostitution scandal that emerged last week, according to a statement Friday from the Secret Service.

The agency also said a 12th "employee has been implicated." The Secret Service previously said a total of 11 Secret Service employees have been under investigation for their part in the incident in Cartagena, Colombia, which came while they were on a security detail in advance of President Barack Obama's trip there for the Summit of the Americas.

In addition, 11 U.S. military service members are under investigation.

Three of those Secret Service employees, including two supervisors, lost their jobs earlier this week.