The defence case is that Mrs Bamber sustained 8 gunshot wounds: 7 entry wounds, 3 exit wounds and 1 non-penetrating wound. This is based on the pathological evidence that the gouge mark to her chest could have been caused by a non-penetrating wound independent of all others.
The above is supported by bullets found in the bedroom: DRH 35 x 2, DRH 5 and DRH 9: 3 from the exit wounds and 1 from the non-pentrating wound. And casings: DRH 3,4,6, 7 x 2, 8, 10, 11, 12, 13, 14 and 43: 8 x gunshot wounds Mrs Bamber and 4 x gunshot wounds Mr Bamber.
The prosecution case is that Mrs Bamber sustained 7 gunshot wounds: 7 entry wounds and 3 exit wounds. This is based on the pathological evidence that the gouge mark to her chest could have been caused by a bullet richochet from one of the other wounds.
The above isn't supported by the bullets found in the bedroom since four were found and the above scenario only requires 3. It also means there's 1 casing too many. Unless you buy into the theory that the rifle malfuntioned as Bamber was walking up the stairs and he ejected a casing on the landing or someone inadvertently carried it upstairs under foot or on clothing. These explanations account for only 3 casings found in the kitchen when Mr Bamber clearly sustained 4 gunshot wounds there.
The most straightforward explanation is that 1 casing (about 5mm x 5mm) was lost in the kitchen. Mrs Bamber sustained 8 gunshot wounds: 7 entry wounds, 3 exit wounds, 1 non-penetrating wound with the four bullets relating to her gunshot wounds. 11 casings found in the bedroom and 1 on the landing relate to Mrs Bamber's 8 wounds and Mr Bamber's 4 wounds.
Obviously I have not included the 2 casings found near Sheila's head as these clearly relate to her 2 gunshot wounds.
I don't believe we can entirely rely on the position of the casings and bullets, but if we are going to do so, then how do they demonstrate that Nevill was shot in the main bedroom? It's being assumed that if there are four casings left, then four wounds must have been inflicted to Nevill in that same room, but the casings seem to be in the wrong place to account for that. I appreciate that they will bounce off walls and so forth (one reason we can't rely on the position recorded), but if Nevill is shot in the main bedroom, there should be more casings on the bed itself and near Sheila's body, not in the area near June's side of the bed. I suppose there is a possibility that Jeremy fired shots to Nevill while facing the exit to the main landing, and the cartridge cases then bounced off the northside wall of the main bedroom and ended up near where June's body would come to a rest.
I think either the casings have been moved within the main bedroom, or a combination of circumstances has occurred in which maybe one or two bullets were never recovered in the main bedroom and Nevill was shot on the main stairs and one or two casings have somehow ended up in the main bedroom, probably because they bounced off the walls and initially ended up on the main landing near the entrance to the main bedroom. In either situation, the movement of the casings was probably accidental/inadvertent.