Two members of the White House team may have been involved with prostitutes during President Obama's April trip to Colombia, according to a report Friday from Fox News.

Fox said it was in possession of a letter from the Department of Homeland Security's Office of the Inspector General (OIG) informing Sen. Susan CollinsSusan CollinsCollins: I'm not working with Freedom Caucus chairman on healthcare Mexico: Recent deportations 'a violation' of US immigration rules White House denies misleading public in aircraft carrier mix-up MORE (R-Maine) that “two non-[Secret Service] personnel may have had contact with foreign nationals.”

In April, 11 Secret Service agents and some members of the military assigned with advance security ahead of President Obama’s trip to Colombia were investigated for allegedly bringing as many as 21 prostitutes back to their hotel.

Six of the agents have been fired, three have been cleared of serious misconduct, and the rest have been suspended pending further investigation.

At the time, White House spokesman Jay Carney said there was “no indication of any misconduct” by any White House staffers.

But earlier this week Fox News reported that some members of the White House team might have been involved in the prostitution scandal.

Following the first Fox report, Sen. Chuck GrassleyChuck GrassleyTrump eyeing second Supreme Court seat Grassley: Another Supreme Court vacancy likely this summer Sweeping change at DOJ under Sessions MORE (R-Iowa) on Thursday sent a letter to White House Counsel asking about the White House’s internal review; if the Obama administration had heard from the IG regarding its Department of Homeland Security (DHS) review; and how the White House would respond if it was determined that staff had engaged with prostitutes on a foreign trip.

Grassley said he was following up on an April letter that he said went unanswered.

“If the report includes the findings that are being reported, how did your initial review fail to uncover the involvement of these staffers?,” Grassley asks in his letter. “Do you concede that your initial review was performed in haste and without sufficient care? If the report includes the findings that are being reported, will Spokesman Carney issue a retraction or correction to his public comments denying any White House staff involvement?”

The OIG letter also reportedly said other members of the White House advance team “may have been” involved, but the OIG did not pursue those leads because it did not involve DHS personnel and was therefore “outside the scope of the investigation.”

The White House on Friday stood by its earlier position.

“As we’ve said for months, the White House review concluded that no members of the White House advance team, either staff or volunteers, engaged in inappropriate conduct during the President’s trip to Colombia,” said White House spokesman Eric Schultz.

Updated at 4:27 p.m.