Thomas Homan, acting director of U.S. Immigration and Customs Enforcement, announced plans to step down on Monday. He’ll retire from the role in June.

When President Donald Trump took office last year, Homan was asked by then-Secretary of the Department of Homeland Security John Kelly to step in as acting director of ICE. Homan, a career law enforcement officer, had reportedly been preparing to retire at the time.

About six months ago, Trump nominated Homan to serve as the permanent director of ICE. According to reports, Homan’s confirmation hearing never took place, at least in part because he was uncertain whether he wanted to accept the role.

While Homan officially attributed his decision to retire to family considerations, some have suggested that it was motivated by tensions with Kirstjen Nielsen, the current DHS Secretary. Three people told The Wall Street Journal that Homan “felt sidelined” during immigration negotiations with Congress and “frustrated” that Nielsen wasn’t “acting quickly enough on his recommendations.”

Due to this frustration, Homan reportedly decided to retire earlier this year, but delayed the announcement at Nielsen’s urging because of an already high turnover rate among senior Trump administration officials.

The news of Homan’s exit comes days after Ronny Jackson, Trump’s pick to lead the Veterans Affairs Administration, withdrew his nomination amid allegations of workplace misconduct.

Homan largely endorsed the administration’s tough immigration policies—immigration arrests increased 40% during his tenure, and 26% of those arrested had no criminal record, up from 13% in 2016.