The former New York City mayor has been under investigation for several years over his business dealings in Ukraine. Details of the search were not immediately available, but it comes as the Justice Department continues its investigation into the former New York City mayor and staunch Trump ally.

The official could not discuss the investigation publicly and spoke to the AP on condition of anonymity. News of the search was first reported by The New York Times.

The federal probe into Giuliani’s overseas and business dealings stalled last year because of a dispute over investigative tactics as Trump unsuccessfully sought reelection, and amid Giuliani’s prominent role in subsequently disputing the results of the contest on Trump’s behalf.

The full scope of the investigation is unclear, but it at least partly involves the Ukraine dealings, law enforcement officials have told the AP.

Giuliani was central to the then-president’s efforts to dig up dirt against Democratic rival Joe Biden and to press Ukraine for an investigation into Biden and his son, Hunter—who himself now faces a criminal tax probe by the Justice Department. Giuliani also sought to undermine former U.S. ambassador to Ukraine Marie Yovanovitch, who was pushed out on Trump’s orders, and met several times with a Ukrainian lawmaker who released edited recordings of Biden in an effort to smear him before the election.

A message left for Giuliani’s lawyer wasn’t immediately returned. Giuliani had previously called the investigation is “pure political persecution.”

Federal prosecutors in Manhattan had pushed last year for a search warrant for records, including some of Giuliani’s communications, but officials in the Trump-era Justice Department would not sign off on the request, according to multiple people familiar with the investigation who insisted on anonymity to speak about an ongoing investigation.

Officials in the deputy attorney general’s office raised concerns about both the scope of the request, which they thought would contain communications that could be covered by legal privilege between Giuliani and Trump, and the method of obtaining the records, three of the people said. The people could not discuss the investigation publicly and spoke to AP on condition of anonymity.

The issue was widely expected to be revisited by the Justice Department once Attorney General Merrick Garland assumed office. Garland was confirmed last month and Deputy Attorney General Lisa Monaco was confirmed to her position and sworn in last week. The Justice Department requires that applications for search warrants served on lawyers be approved by senior department officials.

A Justice Department spokesperson did not immediately respond to a request for comment. The U.S. Attorney’s office in Manhattan declined to comment Wednesday.

—Tucker reported from Washington. Associated Press writer Larry Neumeister contributed reporting from New York.