The House Committee on Oversight and Government Reform has launched an investigation into the White House’s handling of senior aide Rob Porter, who was not issued a permanent security clearance due to allegations of domestic abuse by his two ex-wives.

“Who knew what, when, and to what extent? Those are the questions that I think ought to be asked,” the committee’s chairman, Republican Rep. Trey Gowdy of South Carolina, said Wednesday on CNN.

“And if you knew it in 2017 — and the [FBI] briefed [White House officials] three times, then how in the hell was he still employed? … How do you have any job if you have credible allegations of domestic abuse?”

Republican Rep. Trey Gowdy on allegations of spousal abuse against former top White House aide Rob Porter: “How in the hell was he still employed… How do you have any job if you have credible allegations of domestic abuse?” https://t.co/vuNO7b7riO https://t.co/nHySCCvUGb — CNN (@CNN) February 14, 2018

Trump has publicly defended Porter in the days since the allegations surfaced in the media.