How many movies have Erwin Halletz and Fritz Wepper collaborated on?

They have worked on 4 movies together! Their first movie together was When Night Falls on the Reeperbahn (1967) while their highest rated movie together was On the Reeperbahn at Half Past Midnight (1969). They have not worked together since On the Reeperbahn at Half Past Midnight (1969). They are most known for their crime films together.