(Bloomberg) -- The head of the US governmental office charged with administrating auto recalls and launching federal investigations into safety defects has resigned, a week after government auditors issued a critical report about the division. 

Stephen Ridella, who served as the director of the US National Highway Traffic Safety Administration’s Office of Defect Investigation, resigned from the agency on June 3, spokeswoman Veronica Morales said in a statement. Cem Hatipoglu, an NHTSA associate administrator for vehicle-safety research, will take on Ridella’s responsibilities as the agency searches for a permanent replacement, she said.

NHTSA didn’t provide a reason for Ridella’s departure, though the resignation happened a few days after the US Department of Transportation’s Office of Inspector General published the results of an audit. In the report, inspectors accused Ridella’s office of moving too slow at times, and of failing to properly document investigations.

The agency defended its recent work in an emailed statement about the IG report, pointing to its high volume of safety recalls in recent years. NHTSA also said it had “already fully implemented most of the recommendations” proposed in the audit.

Ridella started a new position this month at Amazon.com Inc.’s autonomous-vehicle subsidiary Zoox Inc., according to his LinkedIn profile. Ridella worked at the NHTSA for 17 years and spent six years at its defect-investigations office

Ridella has been at the center of high-profile NHTSA investigations, including several ongoing probes involving Tesla Inc. In August 2021 and February 2022, the NHTSA opened the investigations into possible Autopilot defects. It’s also been assessing Tesla’s methods for monitoring drivers using Autopilot to ensure their engagement. 

The executive’s departure was first reported by the Associated Press. 

(Adds NHTSA statement on IG report in paragraph 4)

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