German ex-billionaire Madeleine Schickedanz has sued the bank Sal. Oppenheim for damages after losing her fortune in the 2009 insolvency of retail company Arcandor. Schickedanz seeks to prove she was badly advised. In the high-profile lawsuit, which began in the Cologne Higher Regional Court on Tuesday, Madeleine Schickedanz is seeking damages to the tune of 1.9 billion euros ($2.5 billion) from private wealth management firm Sal. Oppenheim and property financier Josef Esch. Schickedanz, who was the former majority shareholder in German retail giant Arcandor, claims Sal. Oppenheim and Esch failed in their duties as her financial advisers. Her lawyer Stefan Homan told the court that Schickedanz had sought a conservative investment strategy, but the two defendants chose the high-risk investment in Arcandor, which, in addition, had only served their own interests. The case goes back to the insolvency of German retail company Arcandor in June 2009, which saw Schickedanz\'s 53-percent stake, worth 2 billion euros, dwindle to 240 million euros. The claimant needed to plausibly prove that she was against investing in Arcandor, Judge Stefan Singbartl said at the beginning of the lawsuit on Tuesday. Schickedanz, now aged 69, was the heiress of the former German mail order giant Quelle, and in 2008 was ranked among the world\'s richest people by Forbes Magazine, estimating her fortune at 3.9 billion euros. In 2009, Schickedanz told German mass circulation daily Bild that she had to live on 600 euros a month. Sal. Oppenheim is now the private wealth management unit of Deutsche Bank after it was taken over by Germany\'s biggest bank in the wake of the Arcandor insolvency filing.