Mr Rooker accused the German authorities of failing to prosecute their inquiry strongly enough, and not even interviewing General Mohnke.
Mr Rooker, became involved in the case because Reg West, one of the survivors of the massacre who lived in his Perry Barr constituency, has since died.
But Hartwig Negendank, the Lubeck state prosecutor, defended his decision not to interview Mohnke during his five- year re-examination of the case.
He told BBC Radio 4 yesterday: 'Anybody who knows about law knows that nobody has to talk to a public prosecutor. Nobody is going to be forced to open up his mouth. Mr Mohnke was once confronted with these incriminating things and he denied it, so what's the use of interviewing him again.'
On 22 April 1988, Mohnke told Bild newspaper in Hamburg: 'I have never concealed a thing. I was in Dunkirk, it's true. But what kind of beasts must they have been to slaughter prisoners of war with bayonets and so on? That's an appalling crime.'
Mr Negendank said a half- baked action against Mohnke would have helped no one.
Albert Evans, 72, who was first shot in the neck and then lost an arm in the explosions in the barn, disagreed. He has watched the other survivors die and recites their names. 'It's not right, all those kids shot dead, and he's living in the lap of luxury. He should be tried. It would clear the air.'