Soon after payment-processing giant Wirecard reported in June 2020 that nearly $2bn had gone missing from its balance sheet, its chief operating officer Jan Marsalek boarded a private jet out of Austria. After a landing in Belarus, he was whisked by car to Moscow, where he got a Russian passport under an assumed name.

Western intelligence and security officials now say they have reached the unsettling conclusion that Marsalek had likely been a Russian agent for nearly a decade.