German airman, pow camps, prisoner of war, German prison guard

[PFSDublin]

I am trying to identify an artist who painted a watercolour of three British RAF fighters at Clausthal POW camp in November 1917. The painting is signed "F.E. Kius" and was given as a gift to a British pow. The surname Kius is German, and the painting is a birds eye view of the three British planes, as if seen from the cockpit of a German plane. I thus suspect that the picture was painted by a German prison guard, perhaps one with prior service in the German airforce. Does anyone have a list of the prison guards at Clausthal in November 1917 that might help identify the artist?