Prior research: Wikipedia article on post-war/occupation era West Germany
This takes place in a very slightly alternate universe.
In 1949-50, who was responsible for the operational aspects of civil law enforcement in occupied Germany? (Specifically, in the US zone.)
My provisional scenario involves a mid-ranking German police officer coming across The Inexplicable (tm) and needing to report it to the appropriate person in the military authority.
However, it seems there was, legally, no "Germany" (even in the East/West sense) until May 1949 and even then it seems reasonable while they could have rebuilt civil administration based on pre-war models actually getting it up and running might take some time.
2) Where in Heidelberg was (/is?) the police headquarters? Was there a "government center" in some part of town?