Luftwaffe airmen - cause of death?
 

Hello all, i am wondering if anyone can help provide me with a cause of death for the following two German airmen?
I presume that they died in a POW camp in England, but was wondering if there is any source to find out exactly what happened to them? They are both buried in Shrewsbury Cemetery.

KNUTEL, Airman, ERICH, German Air Force. 27 July 1944.

SCHIEFER, Airman, GERHARD, German Air Force. 9 December 1944.

Many thanks for any help, Tom