German judges allowed former Audi CEO Rupert Stadler to leave the jail where he’s been since June, while warning that there’s still strong evidence against him in a criminal probe over diesel-emission cheating.

The 55-year-old was told not to contact any potential witnesses in the fraud investigation and must post bail which will be forfeited should he violate the order. The measures were necessary to hedge the risk he may tamper with evidence, the Munich Appeals Court said Tuesday in an emailed statement.

“The court understands that there’s still a strong suspicion against him,” the tribunal said in the release. “But the court considers it tenable and justifiable to release him under conditions.”

His release comes after a successful appeal of a lower court ruling from August that kept him in a prison close to the Bavarian town of Augsburg since his June 18 arrest. Audi suspended him shortly after his arrest and on Oct. 2 announced that he left Audi parent company Volkswagen, where he served on both executive boards.

Stadler was the highest profile executive detained since the diesel-cheating scandal engulfed Volkswagen nearly three years ago. Throughout the crisis, as sanctions topped €27-billion ($31-billion), Volkswagen rejected claims that senior managers such as Stadler were aware of the criminal scheme that stretched over almost a decade.

Audi settled with Munich prosecutors earlier this month for €800-million to end the case against the company, while the probes against individual employees and managers continue.

Investigators added Stadler as a suspect at the end of May and raided his home over allegations of fraud and falsifying public documents relating to 2015 sales of diesel cars in Europe. They said his arrest was warranted because in a wire-tapped phone call he suggested putting a witness on leave, showing he was tampering with evidence.