I m a German historian and prepare an article about the murder of Flying Officer George Arnold Costello in Germany 1944.
I know that George A. Costello´s father was Val Costello from Stonewall, Canada (I checked files of the British National Archives in Kew, London). George A. Costello is burried near Kleve, Germany.
If Val is your grandfather, you should be a nephew of George.
I would be grateful if you could contact me.
Dr. Hans Dieter Zagefka