Well you are going to commit a crime where there are only two possible suspects, the police are not daft it takes a lot to fool them.
JB cannot be seen going to or from the farm, he cannot leave a tell tale mark anywhere, he cannot get marked or injured in anyway. Finally hardest of all he has to make the shot to Sheila look like suicide.
He achieves the impossible then tells everyone it was him by putting the silencer in the cupboard why?
Bamber cycled between 1am - 3am. No one would see him.
Who would injure him? Nevill was shot 4 times before the kitchen fight. Bamber was fully padded up.
He would have used force or persuasion to move Sheila. Not difficult. He had checked on her condition a few hours earlier.
What tell tale marks can he leave. He was in the house regulary.
He had to take the silencer off while inside WHF. He put it away. A thread created this month on why.