( 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 , one Secret Service agent allegedly removed ammunition from his service weapon 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 . No police report was filed and no complaint was filed with the Secret Service by any of the parties involved , a government source told CNN 's Joe Johns Thursday . `` The Secret Service takes allegations of improper behavior seriously and works diligently to investigate and resolve issues . Any misconduct is regrettable , but when it is identified , appropriate action is always taken based on established rules and regulations , '' Edwin M. Donovan , deputy assistant director of the Secret Service , said in a statement . Investigation revisits Secret Service prostitution scandal . The internal investigation was launched as a result of inquiries by the Post , the government source said . That probe led to a routine search of the agent 's agency-issued BlackBerry , the Post reported . The federal law enforcement source confirmed that the agent , a supervisor , and a second supervisor were discovered to have sent sexually suggestive e-mails to a female Secret Service employee . Nothing explicitly suggestive has been found , the government source said . The first supervisor was removed from his position , the source said , but the second supervisor remains on the presidential security detail . The Post reported that the second supervisor was removed from the security detail . 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 prompted new rules of conduct for Secret Service employees in the wake of the incident . Sen. Ron Johnson said at a Senate hearing Thursday that despite assurances from Department of Homeland Security and Secret Service that the 2012 Cartagena prostitution scandal involving presidential detail agents was an anomaly , congress has found similar instances in 17 countries . `` Yesterday we learned that two senior level United States Secret Service agents assigned to the President 's detail were recently disciplined for sexual misconduct . According to whistle-blowers , one of these men helped lead the USSS internal investigation of the sexual misconduct in Cartagena in April of last year . This is like the fox guarding the hen house , '' the Wisconsin Republican said . `` This type of behavior jeopardizes the security of the President of the United States and makes U.S. government personnel susceptible to coercion and blackmail . '' While not addressing the specifics of the most recent case , William Hillsburg , acting director of the Public Affairs Department of the Homeland Security office of the inspector general , said that in the next couple of weeks his office is expected to release an inspection report with an in-depth look at the culture of the U.S. Secret Service . The report will look at whether there 's something in the Secret Service culture that led to the behavior in Cartagena . It will also include recommendations on how agents are trained . Report : No problem with Secret Service response to Colombia scandal .
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 . President Obama was informed of what happened by his chief of staff, Denis McDonough. Source : Those e-mails were sent to a female Secret Service employee .