There's a strong inference the blood, the lab claimed to have found inside the silencer, originated from the shootings and more likely from SC than a combination of NB and June's blood but its not impossible it came to be there from some other method eg at the manufacturing stage or NB lending the rifle/silencer to a.n.other who unassembled to clean and caught self on wire brush. Unlikely but not impossible.
The courts consider the blood/silencer the strongest aspect of the case. Jurors queried the blood evidence with the judge and it seems they were under the impression the blood was a "perfect match" for SC's.
Page 12 of summing up
"Now I think that does complete the evidence of those experts, so it all comes down to this, does it not? Mr Hayward says, "Well to begin with, merely analysing the blood inside the moderator, it correponds with Sheila Caffell's.
Page 13 of summing up
"then come to Mr Fletcher's evidence: "One of Sheila's wounds clearly was a contact wound", so that is entirely consistent with it being her blood in the end of the moderator".
Page 1, 2nd para of summing up/questions from jury
"We need to hear blood expert's evidence regarding the blood in the silencer, (a) a perfect match of Sheila's blood, (b) what was the chance of the blood group being June and Ralph's mixing together"
It
was a perfect match, but yes, only to her blood group.
The 2002 appeal did raise some doubts about how the original flake was tested with it being suggested that it should have been ground into a powder to ensure it was mixed before being diluted instead of cut into 5 pieces. Mark Webster argued that Haywoods test could not be
guaranteed to detect a mixture as opposed to a single source.
However, Mark Webster and Dr Lincoln agreed that the only way of Nevill and Junes blood being mistaken for Sheila's was the 'incomplete intimate mix' theory which Mr Haywood tried to perform tests to replicate. He theorised that the only mechanism for an incomplete mix was for other blood to mix with some that had already dried which was very unlikely given the lack of heat generated within the moderator and probable lack of drying time between June and Nevill being shot.
There were no examples in forensic literature to support such an event and Haywood performed tests on this theory with negative results. He was merely being careful by saying that there was a remote chance of the bloodflake originating from an incomplete mix.
It may have been a good idea for the defence to have advanced the possibility of contamination at the manufacturers, one would assume the baffles are pressed out by machine but assembled by hand. This possibility might be dismissed if NB or anyone else had cleaned the silencer since it was bought.
It is an interesting thought that Robert Boutflour may have cleaned the moderator with a wire brush but the moderator was quite new and bought with the gun AFAIK, I have no idea how often they would need cleaning or if NB wouldn't have just done this himself.
In CALs book, there is a short passage that has RB losing his temper when cross examined on whether he had ever touched the moderator when it was found or had cuts on his hands while doing so. I dimly recall that RW also states that the defence was alive to RBs blood group match which is completely contrary to the CT claim that it wasn't known until 2002. I've never seen a transcript of RBs exam/cross exam so don't know if RB was further questioned about ever disassembling and cleaning the moderator in the past.
In short, the chances of the bloodflake not originating from Sheila were remote. We also have no idea what the jury thought of there being human blood inside the silencer in the first place, no matter who it belonged to. Add in the paint and the jury must surely of had the reasonable assumption that the moderator was attached at some point and assessed the chances of Sheila looking for, attaching, using and then replacing the moderator back in the cupboard while in some kind of psychotic state.
