After watching the LSE video on "You tube" I was very pleased to read this article via an email link online yesterday as it gives some further background information about the policy of "reprisal" and how it was implemented by the Germans.
Unfortunately, there is only a brief mention about the group known as EK 4 (Englaender Kommando 4)
The German Spring Reprisals of 1917: Prisoners of War and the Violence of the Western Front by Heather Jones
German History (2008) 26 (3): 335-356.