Apologies if I am also digressing but I think the problem that David is referring to, is that no mater how much evidence points away from the sound moderator having been used, whether that is anomalies in blood distribution; burn marks; provenance and custodial record; or whatever, the authorities are immovable.
However, there has seemed to be a reluctance on the part of defence / campaign to directly canvas the allegation of deliberate contamination.
Personally I disagree. Sorry.
First, it doesn't need to be intentional contamination; it could have been inadvertent/accidental. The family may even genuinely believe Jeremy is guilty and have introduced the silencer evidence in the genuine, but mistaken belief it is an incriminating artefact. And they may be right about his guilt but wrong on the evidence. It's called being right for the wrong reasons.
Second, an appellate bench does not need to take the view that the silencer was intentionally contaminated. All that needs to be established is that the silencer could have been contaminated. Once that's established, the evidence has to be considered unsafe and the conviction must be quashed. If so, that doesn't mean Jeremy is innocent. Far from it, but the appeal court in that situation isn't being asked to decide guilt or innocence. That's for a jury at a re-trial (though given the passage of time and deterioration of evidence, I would assume in that scenario the Crown will offer no evidence).
Third, I don't believe the issue was simply that any old blood was found in the silencer. I think there was a bit more to it.
It was also that:
(i). probabilistically, the blood had to be assumed to be Sheila's; and,
(ii). the blood must have got there due to a contact/near-contact shot; and,
(iii). the silencer was found in the immediate vicinity of the crime scene.
These points are inter-linked. It was acknowledged that point (i) was not a 99% 'legal certainty', rather it was more a preponderance of evidence on the facts given (ii) and (iii). Normally, the prosecution must prove each vital material point beyond reasonable doubt, but what the Crown were saying here is that although we can't be 99% about the blood, if you look at the other points and consider it all in totality, it does point to Bamber.
In other words, the blood in the silencer contributed to a finding of guilt because it formed part of a bigger picture.
Now, my central point here is that I dispute the view that the silencer fits into a bigger picture. The blood evidence does not support this view. In turn, this is one of the reasons I reject the assertion that the silencer was used.
Furthermore, while I am not alleging intentional contamination, I think the evidence points to it. At the moment, this evidence does not quite rise to proof, but it's enough to warrant further inquiries.
The further inquiries would centre around at least two major avenues:
1. Close documentary analysis of the chain of custody records.
2. Expert opinion on the blood evidence to establish if the blood distribution found matches what would be expected. In particular (among other things), whether passive dripping is a relevant factor allowing for the blood impacting the silencer under ballistic tension.