2 Secret Service supervisors under investigation in misconduct probe November 14, 2013 -- Updated 0555 GMT (1355 HKT) Secret Service is still reeling from a April 2012 scandal involving prostitutes and drinking before a presidential trip to Colombia. Report: A Secret Service agent left behind a bullet in a woman's hotel room Washington Post: The agent tried to get back in, and hotel staff notified the White House Agent, another supervisor under investigation over sexually suggestive e-mails Source: Those e-mails were sent to a female Secret Service employee (CNN) -- Two Secret Service supervisors on President Barack Obama's protective detail are under investigation for alleged misconduct, a federal law enforcement source with knowledge of the internal Secret Service investigation told CNN's John King. The details were first reported in the Washington Post Wednesday night. The investigation began after an incident at the posh Hay-Adams hotel near the White House in May. As first reported by the Post, the agent allegedly removed ammunition and left a bullet in the room of a female guest, whom he had met in the hotel bar. The agent tried to regain entry to the room when he realized the bullet was left behind, the Post said. Hotel staff notified the White House after he identified himself as a Secret Service agent and demanded to be let in to the room. The investigation led to a routine search of his agency-issued BlackBerry, the Post reported. The source confirmed the supervisor and a second supervisor were discovered to have left sexually suggestive e-mails to a female Secret Service employee. The Post said the first supervisor was removed from his position, and the second supervisor has been reassigned. While the paper named the two supervisors involved, CNN is not yet identifying them. The investigation follows the Secret Service scandal in April 2012, involving prostitution and drinking before a presidential trip to Cartagena, Colombia. A review promoted new rules of conduct for Secret Service employees in the wake of the incident. CNN's John King contributed to this report.