The House Oversight Committee has opened an investigation into Rob Porter's White House employment while he was being accused of abusing his ex-wives.

The probe comes as the White House, more than a week into the scandal, has continued to offer shifting explanations of the circumstances of Porter's tenure as a top aide to President Donald Trump.

Wednesday morning, the Oversight Committee's chairman, Rep. Trey Gowdy, R-S.C., sent White House chief of staff John Kelly and FBI Director Christopher Wray letters asking for details about Porter's background check and the decision to keep him on the job before he quit last week.

Gowdy, in his letters, specifically asked for "the date on which any White House employee became aware of potential derogatory or disqualifying information on Porter from the date of his appointment to February 12, 2018, and which individual was notified."

Here is Gowdy's letter to the FBI director: