Hatz, former research and development chief at Porsche and former head of powertrain development at Audi and parent Volkswagen, had been taken into custody in September 2017, a person familiar with the matter said at the time.

The spokesman for the prosecutors office also said that the questioning of suspended Audi Chief Executive Rupert Stadler, who was arrested earlier this month, would continue next week.

(Reporting by Joern Poltz; Writing by Christoph Steitz; Editing by Tom Sims)