William Bradford, the director of the Energy Department's Office of Indian Energy, has resigned from his post in the Trump administration following a senator's request for more information about comments he appeared to have made online.

"William Bradford tendered his resignation this afternoon and is no longer with the Department of Energy," department spokesperson Shaylyn Hynes said in a statement.

On Wednesday, Sen. Ron Wyden, D-Ore., sent a letter to the FBI and Energy Department asking for additional information about Bradford's claim that he was hacked in online commenting service Disqus and had not made offensive comments.

The account under scrutiny contained comments questioning former President Barack Obama's U.S. citizenship and called his mother "a fourth-rate p&*n actress and w@!re."

Bradford was first reported in June to have made offensive comments on Twitter, where he insisted Obama was born in Kenya and said World War II internment camps for Japanese-Americans were necessary.

The now-former Energy official had cited he could not discuss the matter due to "an ongoing federal investigation into multiple cyber attacks and Internet crimes committed against me over the past several years, to include email intrusions, hacking, and impostors in social media."