I would have fought at the time not to have the silencer included because it was removed from the scene , handled by several members of the public in a non forensic manner, handled by the police without gloves , not recorded properly by the CSO and had the exhibit numbers changed. That would be enough for starters.
Also one expert said he could not say 100% that the blood results did not show animal blood and now we see there is a document that says the blood inside could match that of Robert Boutflour?
Plus no one could agree on the "size" of the blood flake which was the only concrete non circumstancial piece of evidence that convicted him at the time
Its just a mess.