In 1971, by now an associate of Rainer Werner Fassbinder, Sedlmayr was briefly arrested because a stolen artwork, the Blutenburger Madonna, was found in his house.

His breakthrough came with the leading role in Hans-Jürgen Syberberg's film Theodor Hierneis oder Wie man ehem.

[1] On 21 May 1993, two half-brothers,[2] Wolfgang Werlé and Manfred Lauber, former business associates of Sedlmayr, were found guilty of his murder and sentenced to life in prison.

In 2009, the two men convicted of the killing took legal action demanding the removal of their names from the German and English language Wikipedia, arguing that it invaded their right to privacy.

[6] In 1973, Sedlmayr won the Outstanding Individual Achievement: Actor Deutscher Filmpreis award for his role in Theodor Hierneis oder Wie man ehemaliger Hofkoch wird.