By Jörn Poltz

Dressed in his trademark black turtleneck and rimless spectacles, the one-time chief executive Markus Braun said he had no knowledge of any forgery or embezzlement and believed he was running a legitimate and healthy business.

Austrian-born Braun, 53, and two other ex-Wirecard managers Oliver Bellenhaus and Stephan von Erffa are on trial on charges including market manipulation and fraud and face up to 15 years each in prison if convicted.

Braun has been in custody since the 2020 collapse of Wirecard, which shook Germany's business establishment, putting politicians who backed it and regulators who took years to investigate allegations against the firm under intense scrutiny.

"I had no knowledge of counterfeiting or embezzlement," Braun told a court in Munich, describing the discovery of 1.9 billion euro ($2 billion) hole in Wirecard's balance sheet as a "day of pain" for shareholders and employees.

In the opening exchanges of the trial last year, Bellenhaus, who became a key witness after turning himself in to the authorities, painted Braun as an "absolutist CEO" calling the shots at the heart of a vast swindle.

Braun, who has spoken only briefly before at the trial to confirm his personal details, pushed back against that characterisation, saying he had relied on what he believed to be proper accounting and auditing.

At the start of a testimony that is expected to go on for several days, Braun retold his early years at Wirecard, describing a struggling startup where he and other managers pulled all-nighters and worked with a sense of mission.

"There was in reality no life outside the company," he said, speaking throughout in a calm and concentrated voice.

At the start of the trial in December, prosecutors accused the defendants of being part of a gang that invented vast sums of phantom revenue through bogus transactions with partner companies to mislead creditors and investors.

Braun's lawyers have alleged that Bellenhaus was the main perpetrator of the fraud at Wirecard, which began processing payments for pornography and online gambling and rose to be a blue chip DAX company worth $28 billion.

(Reporting by Jörn Poltz and Alexander Hübner; Writing by Matthias Williams; Editing by Mark Potter)