Im trying to find the best way to search my family in Germany and I have come to a brick wall and im hoping someone can help me please?

Willi Mehlitz (1897 - 1976) and his family lived in Küstrin in the 1940's Ive been able to find one entry on the internet in regards to him but non to his wife:
Margarethe (maiden name Kliemann.

I know he was, unfortunatley, a member of the Schutzstaffel, and i have photos of him in this, though im not able to find out his rank from this, as i dont understand all the different badges and insignia.

If anyone can help with advice on either the family or finding information about his time in the army id be really greatful please, as i know nothing at all