The indictment reopens the question of whether other senior VW executives knew about the scandal, which has dogged Europe's biggest automaker for more than 2-1/2 years and led to a regulatory crackdown that is threatening thousands of jobs as customers increasingly shun diesel-powered cars.

The indictment of Winterkorn, who resigned days after the scandal became public in September 2015, is likely to be largely symbolic. Resident in Munich, VW's former CEO is currently in Germany which does not extradite its citizens to non-European Union countries, its Justice Ministry said on Friday.

VW had initially suggested only lower-level managers knew of the cheating. But the indictment alleges Winterkorn agreed with other senior VW executives "to continue to perpetrate the fraud and deceive U.S. regulators".

A lawyer for Winterkorn in Germany did not immediately comment. Winterkorn in January 2017 told German lawmakers he had not been informed of the cheating early, and would have halted it had he been aware.

Here are the details of who is investigating and who is being investigated as part of the "Dieselgate" scandal in both Germany and the United States:

GERMANY:

The bulk of "Dieselgate" lawsuits are being handled by prosecutors in Braunschweig where four separate sets of criminal proceedings are being conducted against current and former managers of VW, headquartered in nearby Wolfsburg.

Some 39 individuals including Winterkorn are being investigated over suspected emissions fraud, with the former CEO also being probed for suspected market manipulation together with Hans Dieter Poetsch, the group's former finance chief who is now supervisory board chairman, and Herbert Diess, now group CEO who joined the firm in July 2015 as head of the VW brand.

The manipulation refers to allegations that VW delayed disclosing market-sensitive information related to its cheating.

Neither Poetsch nor Diess have publicly commented on the investigations, but VW has said it considers the proceedings to be unfounded.

Braunschweig prosecutors are also investigating seven people over suspected falsification of carbon dioxide (CO2) emissions and data deletion.

Prosecutors in Munich, state capital of Bavaria where VW's Audi brand is based, are investigating 18 current and former employees of the premium carmaker over suspected manipulation of diesel engines.

A former Audi engine chief who subsequently became a member of the executive board of VW's sports-car brand Porsche was arrested last year and remains in custody. Audi is suspected of having created the so-called defeat devices years before parent VW used them to cheat emissions tests. Audi denies this.

Prosecutors in Stuttgart, home to Porsche, are investigating Matthias Mueller - group CEO between Winterkorn and Diess - as well as Winterkorn and Poetsch over suspected market manipulation. The three sat on the executive board of VW's majority stakeholder Porsche when the alleged violation of Germany's securities trading law took place.

Stuttgart prosecutors are also investigating three current or former employees of sports-car maker Porsche. These include development chief Michael Steiner and head of powertrain development Joerg Kerner, sources familiar with the matter have said. Porsche has denied the prosecutors' accusations against all suspects. Steiner and Kerner couldn't be reached for comment.

UNITED STATES:

In total, nine people have been charged and two former VW executives have pleaded guilty and been sentenced to prison terms. One Italian citizen, former Audi manager Giovanni Pamio, is in Germany awaiting extradition. Pamio's lawyers have said he is cooperating with prosecutors and has denied the allegations.

Six former senior VW managers charged, including Winterkorn and ex-VW brand development chief Heinz-Jakob Neusser, are believed to be in Germany and have avoided facing U.S. prosecutors. Neusser's lawyer has declined to comment on the charges.

(Reporting by Andreas Cremer, Jan Schwartz, Joern Poltz and Sabine Wollrab; Editing by Mark Potter)