The New York Times says U.S. states attorneys general are accusing Volkswagen from withholding critical documents from their investigations into the automaker’s admission that more than 500,000 cars and SUVs in the U.S. were illegally polluting.

The report says that Volkswagen is citing a notoriously strict German law that protects data and documents from investigations overseas, and that their own investigations have stalled — similar to what federal regulators said when they filed a lawsuit against the automaker on Monday seeking billions.

Volkswagen didn’t comment on the report.

The New York Times said that states attorneys general such as New York’s Eric Schneiderman have said that their limited information is keeping them from identifying the culprits at Volkswagen who may have known about the cheating devices.

“Our patience with Volkswagen is wearing thin,” Schneiderman told the New York Times. “Volkswagen’s cooperation with the state’s investigation has been spotty — and frankly, more of the kind one expects from a company in denial than one seeking to leave behind a culture of admitted deception.”

Schneiderman isn’t alone.

“I find it frustrating that, despite public statements professing cooperation and an expressed desire to resolve the various investigations that it faces following its calculated deception, Volkswagen is, in fact, resisting cooperation by citing German law,” Connecticut’s attorney general George Jepsen told the New York Times. “We will seek to use any means available to us to conduct a thorough investigation.”

Volkswagen faces dozens — if not hundreds — of lawsuits relating to its illegal “defeat device” that it installed on diesel cars beginning in 2009. In a filing by the Justice Department on behalf of the Environmental Protection Agency on Monday, officials from the environmental agency said Volkswagen hadn’t yet proposed a viable solution to fixing its cars.

On Thursday, a German newspaper said Volkswagen was preparing to buy back more than 100,000 cars in the U.S. — presumably older models that can’t be fixed.