The crime series Tatort first aired on 29 November 1970 with the episode Taxi nach Leipzig. From the start, it was a fixed Sunday evening slot that the participating broadcasters were to fill on their own. Each regional broadcaster of ARD is responsible for its own area and sets its episodes there. Since the late 1980s, every episode has run about ninety minutes. The opening credits have hardly changed, and Klaus Doldinger’s theme music from 1970 was modified only in 1979 and 2004. Inside this frame, some episodes break completely with the usual form. One, Murot und das Murmeltier, is set in a time loop.