At trial nothing was made of the burn marks. The CoA doc makes reference to them only ie the fact they were there:
42. The examination of Nevill Bamber's body also revealed black eyes and a broken nose, linear bruising to the cheeks, lacerations to the head, linear type bruising to the right forearm, bruising to the left wrist and forearm and three circular burn type marks to the back. The linear marks were consistent with Mr Bamber having been struck with a long blunt object, possibly a gun.
The pathologist's report headed up "Statements - report of PM Then second statement following questions of counsel" states the following:
"Injuries to Mr Bamber (other than gunshot)
Head wounds (from butt of gun?)
Arm wounds (from barrel of gun)"
http://miscarriageofjustice.co/index.php?action=dlattach;topic=206.0;attach=742
In the ITV docu shown circa Apr '12 Mark Williams Thomas states at circa 16.30 in that the wounds were inflicted the night of the tragedies. He then goes on to explain about tests being carried out 8-)(--)
http://www.youtube.com/watch?v=_i2CjYDJGTo
Did the pathologist make a mistake and omit the burns in his statement above? Seems unlikely to me given the high profile nature of the case and the fact he was being asked specific questions by counsel. 8-)(--)
The location and nature of the marks makes them irrelevant to the murders. There was no way to assess when or how they got there. Because they were on the back, even if they were made during the murders they are of no value of explaining any detail of importance. The wounds to his arms were defensive wounds which is significant in establishing he was still conscious at the time and defending himself. The linear wounds are consistent with being struck by the rifle as he blocked with his hands. The blows to his head would have rendered him unconscous and are what broke the stock. The punches to his face would have been delivered face to face and thus would have resulted in evidence being left on the killer in some fashion and relate to the strength of the killer and height etc.
The wounds to the back do not tell us anythign significant about the murders or who could have committed them. That is why they were ignored at trial and ignored in discussions about the case.
We don't know when they were made or what made them and will never know. Evne if we were to somehow find out it would not help provide any evidence of who committed the murders or significantly change how the killings went down. The location, nature and sheer uncertainty as to when they were inflicted makes them a red herring.
If you want to build a case you stick with the main issues proving the main actions of the killer that resulte din death. If you want to attack a case you attack those pillars proving guilt. When you can't then you resort to red herrings instead hoping to deflect attention from the pillars or lack thereof.
It is a waste of time for us to ponder these marks because:
1) We have no way of ever knowing whether they were pre murder or not
2) no way of knowing if they were scabs or what the nature was because the skin wasn't tested in detail to assess so no way of ever knowing what made the marks
3) the location and nature even if inflicted during the murders doesn't have any way to impact our understanding of who committed the crimes. There are wounds that offer interpretative clues but these are not among those
Our speculation about the marks thus would be a total waste of time.