WASHINGTON (AP) — The Justice Department official leading the investigation of big tech companies’ market dominance is stepping aside from the department’s Google probe because of his previous lobbying work for Google as a private attorney.

Assistant Attorney General Makan Delrahim, the department’s antitrust chief, is recusing himself from the investigation into Google, a person familiar with the matter said Tuesday. Word of Delrahim’s recusal came as other Justice Department officials met with state attorneys general to discuss their parallel investigations of Google and cooperation in enforcing antitrust laws in the tech industry.

The person wasn’t authorized to discuss the investigation and spoke to The Associated Press on the condition of anonymity.

Delrahim lobbied on Google’s behalf in 2007 when the Mountain View, California-based search giant faced antitrust scrutiny over its acquisition of DoubleClick, a competitor in digital advertising.

The Justice Department’s ethics office apparently found no potential conflict of interest when Delrahim sought guidance as the investigation of Facebook, Google, Amazon and Apple began last spring. But as the competition probe progressed, Delrahim “revisited” potential conflicts with the ethics staff, and he and the ethics office “have decided that he should now recuse himself from a matter within the tech review in an abundance of caution,” said a department statement, which did not mention Google.

Associate Deputy Attorney General Ryan Shores will continue to oversee the tech review, the statement said.

Shores, Deputy Attorney General Jeffrey Rosen and staff of the antitrust division met at Justice Department headquarters with state attorneys general “to continue strengthening their multilateral antitrust law-enforcement cooperation concerning technology markets,” the department said in a separate statement. “The Department of Justice looks forward to continued bipartisan cooperation with the states.”

Attorneys general for 50 states and territories are participating in the Google investigation, taking a deep look into the company’s advertising business. They have asked Google for internal documents related to how it sells ads and tracks the behavior of people who use its search engine and other products.

Google, owned by Alphabet Inc., was fined a record $2.72 billion by European regulators in 2017 for abusing its dominance of the online search market. In the U.S., the Federal Trade Commission made an antitrust investigation of Google but closed it in 2013 without taking action.

Scrutiny of Big Tech has deepened and widened across the federal government, U.S. states and abroad. The FTC also is conducting a competition investigation of the four tech giants. In addition to their probe of Google, state attorneys general from both major political parties have opened an antitrust investigation of Facebook.

The House Judiciary subcommittee on antitrust has been conducting a sweeping bipartisan investigation of the big tech companies and their impact on competition and consumers.

Delrahim has suggested in speeches that he’s taking a broad view of how competition is harmed, when assessing whether big tech firms should be broken up. He also has made clear that he is aware that just two companies dominate digital advertising, though he hasn’t named the two, Google and Facebook.

Justice Department and FTC officials haven’t publicly named the companies under investigation or indicated whether they plan to move against any particular company.

The companies have said they’ll fully cooperate with the investigations. But in congressional testimony, their executives have pushed back against accusations that they operate as monopolies, laying out ways in which they say they compete fairly yet vigorously against rivals in the marketplace.

Delrahim’s recusal was first reported by The New York Times.