The House Intelligence Committee wants to interview President Donald Trump’s personal bodyguard-turned-White House aide Keith Schiller for its probe into Russia’s election meddling, ABC News reported Thursday.

Sources familiar with the investigation said that Schiller was one of several Trump associates on the House’s witness list, but did not explicitly say why lawmakers wanted to speak to him. After years overseeing security for the Trump Organization, Schiller now serves as the director of Oval Office operations.

The President dispatched Schiller to FBI headquarters to hand-deliver the letter of termination for former director James Comey, a decision that raised eyebrows in the intelligence community and on Capitol Hill.

The former New York police officer has worked for Trump for nearly 20 years and has been by his side during his transition to politics, working security at campaign events alongside longtime Secret Service officers and ultimately following him into the White House.

Other associates of the President on the House’s witness list include ousted National Security Adviser Michael Flynn, political gadfly Roger Stone, Trump’s son-in-law and adviser Jared Kushner and former campaign chairman Paul Manafort.