Adler,
I am not churching anything up, the Wehrmacht didn't start off executing Soviet POW's, this started after the partisan attacks and mutilation of captured Wehrmacht troops. But the Soviet POWs were neglected from start to finish, and simply because there was no way of feeding them.
The murder of soviet POW's was mainly carried out by the shooting squads the Gestapo. They started it, and the Soviets followed up on it by murdering and mutilating what ever Germans they could capture, and this often meant Wehrmacht soldiers. And so the Wehrmacht carried out their own reprisals, which remarkably weren't worse than they were. Seeing ones buddy mutilated in the manner that some of the captured Wehrmacht soldiers were would send nearly any soldier into a bloodlusting rage.