Kammler was an engineer/scientist and I think he was in charge at sites like Peenemunde. He had been ordered to execute all scientists and engineers at the sites under his command, but saw to their evacuation to Bavaria instead.
He was also alleged to have negotiated a secret deal with the British regarding the surrender of elements within the SS. I suppose he was spared the Nuremberg trials because the allies were more interested in the surviving scientists continuing their work for them and this was his reward for disobeying Hitler's orders.