I can see the point but is it possible a "non practising barrister" isn't practising because he isn't very good?
Rivlin and Lawson were both top QCs and understood that trials are not just about facts and evidence but some theatre too.
As unlikely as it sounds, Sheila finding the silencer, shooting everyone except herself and then putting it back in the cupboard was the only real option for Bamber save for some weak suggestion of accidental contamination.
Otherwise, he is confidently ignoring the expert scientific evidence and alleging serious charges of perverting justice against the Boutflours/police based on a conspiracy theory. He was already claiming a number of others had lied about him, some with motive and some without.
The issues you raised above were explored to the extent they could be; I am a little confused about DBs attempts to unscrew the moderator but AFAIK, that's all that was admitted to, an attempt. Likewise, if they did attempt to scrape blood with a razor blade, this would be the exact opposite of a frame as they would be destroying evidence.
As for accidental contamination, this was also explored to the bounds of any credible defence.RB denied handling the mod and denied having any cuts. The idea that a bucket containing watered down menstrual blood could have been the source of a dried flake found trapped between the baffle plates is laughable - what would the expert witnesses answer have been?
As the 2002 appeal judgement makes clear, JB was also keen to avoid any mention of his intention to sell the farms, including the land that NB had secretly purchased and so could not supply a motive for this dastardly and unlikely plot
Did the relatives know SCs blood group? Did they know RB was a group match?
Did they know there were no photos of the underside of the mantel?
The short answer ( brevity isn't my strong suit !) is simply that Arlidge would have ridiculed any serious attempt to raise a conspiracy and left the jury with the impression that Bamber was simply desperate.
But how much reliance can be placed on the so-called scientific evidence that emanated from the FSS lab?
1. Parliament has already acknowledged quality failings during the 80's at 3.3.1:
https://publications.parliament.uk/pa/cm201011/cmselect/cmsctech/writev/forensic/m61.htm2. I believe at some stage a diagram was drawn depicting the blood supposedly found inside the silencer but what about photographic evidence?
3. The chain of custody from the find of the silencer to its initial examination at the lab on 13th Aug is highly questionable. However it wasn't until 12th Sep and after the silencer had been placed in the cyanoacrylate fuming chamber that we are told a flake of blood was found measuring a 1/4 of an inch.
4. The tests used at the time to examine blood groups were based on blood serology with 8% of the white British population sharing these groups ie it was impossible to say the blood originated from SC only that the flake matched her blood groups shared by many others including Robert Boutflour although I'm not suggesting he dobbed his own blood in there.
5. If the blood flake was found inside the silencer as claimed by FSS it doesn't tell us how it came to be in there. The prosecution alleging it was as a result of SC's contact gsw's doesn't mean it happened this way.
6. Why was the silencer/flake the only blood stained exhibit capable of generating not only the ABO group but also an enzyme and 2 proteins which was over and above anything other exhibits generated.
7. It is known that blood serology testing requires blood stains of a certain quantity and quality to generate results and that environmental insults by way of heat and humidity can degrade samples rendering them useless for testing. We have to believe not only was the blood/silencer capable of generating results over and above other exhibits but it was also capable of withstanding hot gases from firearm discharge and humidity from the cyanoacrylate fuming chamber.
8. The prosecution argued the 'drawback phenomenon' resulted in blood depositing in the silencer ie blood from a contact gsw travelling back against the line of fire. No other case exists where blood has entered a silencer as opposed to a gun barrel. The phenemenon is in large part caused by the hot discharge gases entering into the wound as opposed to dissipating in the atmosphere but this is the case with a barrel sans silencer. With a silencer the hot gases cool and dissipate in the silencers chamber and are slowed through a series of baffle plates.
9. When the drawback phenemenon does occur it presents with large calibre firearms, high velocity ammo and head shots none of which feature in this case with regards to SC.
10. When blood presents as a result of drawback it usually includes tissue but no tissue was present in this case.
11. When blood presents as a result of drawback it usually involves headshots which NC sustained but his blood groups were not found in the silencer.