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.

Assistant Attorney General Makan Delrahim is recusing himself from the investigation into Google, a person familiar with the matter said Tuesday. 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 internet company faced antitrust scrutiny over its acquisition of DoubleClick, a competitor in digital advertising.