Munich prosecutors said on Thursday they had indicted four more former Audi managers (VOWG_p.DE) in relation to alleged cheating on emission tests for diesel engines.
The four are accused of fraud, false certification and criminal advertising, the prosecution office said in a statement.
Business daily Handelsblatt and Reuters had already reported on the move, citing people close to the proceedings.
The indictment, directed at three former board members and one head of department who is already retired, relates to a total 434,420 cars of the Audi, VW and Porsche brands which were mostly sold in the U.S. and Europe, it said.
The four are accused of having prompted the development of engines steered by an illegal software function which made engines produce lower emissions when operating in test conditions than when in regular driving operations.
The prosecution asserts that the accused former board members knew of the practice at various times between October 2013 and September 2015 and still carried on with sales, or did not prevent them from taking place.
In addition, one of the former board members is accused of having known but kept silent about his involvement in the practices ahead of his board membership from 2016, thus fraudulently earning board member pay.
Former chief executive Rupert Stadler and three other defendants were charged last year over their roles in the cheating scandal after parent group Volkswagen and Audi admitted in 2015 to having used illegal software.