At the same time, he lost a great amount of capital, which was confiscated when his son-in-law, the Hanover court Jew Isaac Behrends, went bankrupt and Lehmann was accused of having illegally held back securities, jewels and money from the estate for him (the allegation was never verified). The Hannover "Justizkanzlei" (chancellery of justice) wanted him on trial in Hannover, but the Prussian king, Frederick William I, refused the extradition of his Protected Jew, and a heavy dispute continued for years whether Hannover or Lehmann's Prussian domicile of Halberstadt was the legal venue. Meanwhile, Lehmann tried to bring about a settlement with the Behrens' creditors by partly renouncing his own claims and encouraging the other Jewish creditors to do likewise. He also protested in several letters to King George I, who was also the Hannoverian sovereign, against his relatives' five years' imprisonment and ultimate torture (which did not yield the expected confession of the alleged embezzlemement). There were further losses, so that in 1727 Berend Lehmann's own insolvency was declared. The causes of his failure have not yet been researched. Neither is it clear how he, all the same, succeeded in setting up several foundations. One of them was to hold money to facilitate the marriages of poor orphan boys and girls in the Halberstadt community, another was to secure the livelihood of his "yeshiva" scholars. It served its purpose for the following two centuries.