Bochum: Germany's former top spy, accused of hiding some 15 million euros from the tax authorities, went on trial on Monday.
Werner Mauss, 76, dubbed the "German James Bond" had often been sent on classified operations abroad, but it is his secret financial dealings that are now under scrutiny.
He risks up to 10 years in jail if found guilty of shortchanging the state out of 14.5 million euros ($16 million) in taxes and some 795,000 euros in other contributions between 2002 and 2013.
Prosecutors accuse Mauss of placing large sums of undeclared funds in offshore accounts, including in the Bahamas, national news agency DPA said.
Mauss denies any wrongdoing and claims the business fronts were set up to channel funds used in relation to hostage freeing operations.
The retired agent, who appeared in court wearing a navy parka with the hood pulled over his head, declined to make a statement on the first day of his trial in the western city of Bochum.
His lawyers said Mauss was unable to mount a "proper defence" because he was still bound by confidentiality agreements linked to his decades of undercover work.
Investigators first got on his trail after one of his aliases was found among names of UBS account holders on a CD which the state of North-Rhine Westphalia had purchased from a whistleblower, according to business daily Handelsblatt and Sueddeutsche Zeitung.
Mauss had allegedly failed to declare an account that he holds with the Luxembourg subsidiary of UBS.
He was briefly detained in late 2012 before making a four-million-euro payment to the tax office. He also paid bail of one million euros, according to the indictment read out in court.
After the UBS revelation, his name subsequently emerged in connection with several shell companies listed in the so-called Panama Papers -- leaked documents from Panamanian law firm Mossack Fonseca that exposed the murky offshore financial dealings of the rich and famous.
During the trial, the court will seek to clear up if the letterbox companies were used to pay for "humanitarian actions" linked to his assignments, as Mauss claims, or if they were simply created to hold illicit income.
On his website, Mauss says he was "involved in the smashing of more than one hundred criminal groups and in the arrests of around 2,000 individuals" during his long career in the secret services.
He notably claims to have helped negotiate the release of hostages in Colombia, and boasts of tracking down 41 barrels of toxic waste that had gone missing after an explosion at a chemical plant in Italy in 1976.
His trial is expected to last until December.
