BMW premises in both Germany as well as Austria were searched by German prosecutors, trying to find evidence of defeat devices that can manipulate exhaust emissions.

Some 100 police and law enforcement officials went through BMW’s headquarters in Munich, as well as the automaker’s research facilities and a factory in Austria, specifically the Steyr plant, which assembles 6,000 engines per day and employs about 4,500 people.

Prosecutors said that an investigation has been opened last month against an unknown number of persons suspected of fraud, as reported by Autonews.

“There is an early suspicion that BMW has used a test bench-related defeat device,” said prosecutors in a statement.

However, BMW claims that the findings did not reveal a “targeted manipulation” of emissions readings and that the prosecutors were looking into “erroneously allocated” software in about 11,400 vehicles comprised of BMW 750d and M550d models.

Last month, the automaker recalled 11,700 cars in order to fix an engine management software issue, saying that the wrong programming had been installed. On a more positive note, the German Federal Motor Transport Authority (KBA) gave the BMW 320d a clean bill of health recently, deeming it to be fully compliant with all legal requirements.