Der Fall Deruga (1938)

The physician Dr. Deruga is suspected of having poisoned his wife out of greed. She died after naming Deruga, poor and in debt, the sole heir in her will. There are a lot of people willing to testify against him in court, including Marta, the dead woman's best friend. Only his niece Mingo believes him to be innocent and goes out on her own to prove it.