Four former bankers at Sal Oppenheim, the German private bank acquired in 2010 by Deutsche Bank, have been convicted of criminal breaches of trust stemming from investments badly hit in the 2008 financial crisis.

Four former bankers at Sal Oppenheim, the German private bank which was acquired by Deutsche Bank in 2010, have been convicted of criminal breaches of trust over investments that were hit during the financial crisis, media have reported.

Three of the four men were told they could face prison sentences after being found guilty by Sabine Grobecker, presiding judge at Cologne regional court.

The judge reportedly said the men’s actions took place in a climate of negligent supervision but the multimillion euro losses were “deserving of punishment”. The men did not enrich themselves personally from the transactions, the court found.

The four liable partners include Christopher von Oppenheim, a descendant of the 17-year-old who founded the bank in the year of the French Revolution, and Matthias Graf von Krockow. The four partners left the firm when Deutsche Bank acquired it for €1 billion.

A report by the Neue Zürcher Zeitung said the penalty for Matthias Graf von Krockow (65) would be between two and three years. Christopher von Oppenheim (49) would face a minimum sentence of one year and ten months and a maximum sentence of two years and ten months. Dieter Pfundt (62), the third person facing a possible prison term, would have been unable to adapt to a range between a minimum of 20 months and a maximum of two years and eight months. The fourth man in the case is Friedrich Carl Janssen (70), NZZ said.

A report by the Financial Times said that when the trial began two years ago, prosecutors alleged that the Sal Oppenheim partners were involved in lending €380 million ($430 million) to Madeleine Schickedanz, a mail order heiress, so she could increase her stake in Arcandor, a struggling retail and travel group. Schickedanz is not accused of wrongdoing.

The effect of the loan was to increase Sal Oppenheim’s exposure to an Arcandor bankruptcy, the report said.

By the time Arcandor filed for insolvency in 2009, Sal Oppenheim and a linked company held a stake of more than 28 per cent. In 2007, the last year before the financial crisis, Sal Oppenheim had a €41 billion balance sheet and €2.2 billion of equity. The next year it reported a €117 million loss, its first since the second world war.

Since the financial crisis, a provision in German criminal law for prosecutions over “breach of trust” has allowed prosecutors to charge bankers at a number of institutions, contrasting with the situation in the UK, where no senior figures have faced the risk of criminal sanctions.