Deputy US Attorney Rod Rosenstein submitted his letter of resignation Monday, effective May 11.

Rosenstein was appointed by US President Donald Trump and oversaw the investigation into Russian interference in the 2016 election conducted by Special Counsel Robert Mueller. He was sworn in in April 2017.

In his letter to Trump, Rosenstein wrote:

I am grateful to you for the opportunity to serve; for the courtesy and humor you often display in our personal conversations; and for the goals you set in your inaugural address: patriotism, unity, safety, education, and prosperity, because “a nation exists to serve its citizens.” The Department of Justice pursues those goals while operating in accordance with the rule of law. The rule of law is the foundation of America. It secures our freedom, allows our citizens to flourish, and enables our nation to serve as a model of liberty and justice for all.

Trump had previously nominated Jeffrey Rosen, the current Deputy Secretary of Transportation, to replace Rosenstein.