Trump's longtime bodyguard turned White House aide Keith Schiller eyed in House's Russia probe, sources say

Keith Schiller is now a White House aide.

— -- Congressional investigators want to interview Keith Schiller, President Donald Trump's longtime bodyguard turned White House aide, as part of their investigation into Russian interference in the 2016 presidential election, sources familiar with the investigation told ABC News.

The committee's focus on Schiller and other Trump campaign officials and associates marks a new phase in the investigation, which is examining how Russia attempted to influence the election, the Obama administration's response and allegations of collusion between Trump associates and Russian officials.

Kushner, Stone, Flynn and Manafort have all volunteered to cooperate with the investigations and have denied any wrongdoing.

Committee aides declined to comment about the addition of Schiller to its list of witnesses for ABC News. He did not respond to repeated requests for comment about the investigation.

A former New York police officer, Schiller has been at Trump's side for nearly 20 years and is one of his closest advisers and aides — playing the role of a body man, confidant and gatekeeper.

Schiller accompanied Kushner on an April visit to Iraq with Marine Corps Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff.

ABC News' John Santucci contributed to this report

Editor's Note: A previous version of this story incorrectly stated Schiller visited Iraq with Jared Kushner and national security adviser Lt. Gen. H.R. McMaster. Schiller visited Iraq in April with Jared Kushner and Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff.