Kurtl,
In Ring/Barbas' "Jagdgeschwader 27" is very short mention about Lt. Eberhard Müller - indeed he was shot down on 25 July 44 and his name is indicated as "vermisst”. He had no victories.
Fels am Wagram was base of II./JG 27 since 7 June 44 to 26 August 44
http://www.ww2.dk/air/jagd/jg27.htm
Hope I could help,
Nef