I am currently readingHeinrich Himmler: The Sinister Life of the Head of the SS and Gestapo” by Roger Manvell and Heinrich Fraenkel. Dietrich Bonhoeffer is referred to in this work. The first reference says:

The Abwehr had been a failure, staffed by amateurs and used as a convenient cover by a number of members of the resistance, such as Dietrich Bonhoeffer and (Eberhard) Bethge, Hans Bernd Gisevius, Otto John and Josef Muller (173-174).