Germany's richest woman and heir to the BMW car empire has been spared an embarrassing court appearance after her playboy lover admitted to defrauding her of millions of euros and attempting blackmail with intimate footage of their encounters.

Helg Sgarbi, a Swiss former investment banker, confessed in a Munich court on Monday to having defrauded Susanne Klatten, a member of the reclusive Quandt dynasty, and three other wealthy women of more than euro 9m ($11.3m). He was sentenced to six years in prison.

The case has made headlines in Germany ever since Mrs Klatten went to police to expose Mr Sgarbi, 44, after he demanded euro 49m to prevent a secretly recorded video of their tryst being leaked to the press, colleagues and her husband.

In only interview to date, Mrs Klatten told Financial Times Deutschland in November that she had decided to call in police "in a moment of clarity".

"You are now the victim and you must fight back," she said.

By the time police were called Mrs Klattten had already handed Mr Sgarbi a cardboard box containing more than euro 7m in bundled euro 500 notes to help him pay-off a fictitious Mafioso whose child he claimed to have injured in a traffic accident.

Prosecutors alleged that Mr Sgarbi, who worked for Credit Suisse in the 1990s and speaks six languages, seduced a string of married women "with high criminal energy" in luxury spa hotels across Austria and Switzerland.

After defrauding these women of millions of euros he is suspected of channelling some of the funds to an accomplice, who is under house arrest in Italy and is alleged to have connections to an obscure cult.

Mr Sgarbi did not reveal the whereabouts of the missing funds or the video tape on Monday but told the court he "deeply regretted" the events and wished to apologise to the women involved.

Mrs Klatten is the world's 55th richest person, with a fortune of $13.2bn, according to Forbes magazine.

Although she has always tried to avoid the public gaze, Ms Klatten's savvy as an investor recently has seen her draw more attention than any of her siblings. Alongside her 12.6 per cent BMW stake, for years she held 50.1 per cent of Altana, a German chemicals and drugs company. In 2006 Ms Klatten seized the opportunity offered by buoyant stock markets to push Altana into selling its underweight drugs unit for euro 4.5 bn.

Ms Klatten received euro 2.3bn as a special dividend in spring 2007, a cash pile that she decided not to re-invest immediately given first signs of an economic downturn. She waited almost a year to put euro 300m into Nordex, a German wind-turbine maker, and launched a euro 910m offer for the 49.9 per cent of Altana she did not own in late 2008, the company's share price having halved in the previous year of economic woes.

Copyright The Financial Times Limited 2009