The lead federal investigator into the Colombia prostitution scandal said for the first time Friday that White House personnel may have been involved -- despite administration claims to the contrary. 

Charles Edwards, the acting inspector general for the Department of Homeland Security, wrote in a letter to Sen. Susan Collins that his office's investigation into the April incident found "two non-(Secret Service) personnel may have had contact with foreign nationals." 

The letter came two days after a FoxNews.com report revealed possible White House team involvement. 

One of those employees, Edwards wrote, was a Defense Department employee "affiliated" with the White House Communication Agency. 

The other, he said, "may have been" affiliated with the White House advance team. 

However, Edwards wrote that the office did not pursue those leads "because they are not DHS personnel."