From an office in Dania Beach, consumer protection attorney Yechezkel “Chezky” Rodal is chasing a half-century-old paper trail across three countries to piece together a $3 billion lawsuit against Deutsche Bank companies.

The suit alleges that the bank refused to return billions of dollars to heirs of a Jewish textile magnate whose family fled Nazi Germany. The accounts date back more than 80 years and cross into Spain and Switzerland, where the trail goes cold in the 1990s.