A single fiber and a tiny teeny GSR particle that was most probable the result of cross contamination (no, it was not deemed unreliable due to a technicality, it was deemed unreliable because it was found after the jacket in question was handled by multiple police officers, people who handle guns quite often). And that fiber was not anything rare, it was just a polyester, dyed with commonly used dyes. These are very dubious pieces of evidence.
Also, BG is a creep and a stalker, but also has very low intelligence levels. He was literally caught either in the act, or because he was egregiously bad in covering his tracks. I cannot believe that a man like that, caught in Kensington Palace with a burglar kit, would be able to commit this particular murder without leaving a highway of traces behind and, considering he is a narcissist, that he would be able not to brag that he commited such a notorious crime.
There is also a question of "how". JD's flat was in a residential area, just houses, no shops or other public places. It's not an area where a criminal could just casually hang out waiting for an attractive woman to appear, without catching a ton of unwanted attention from the locals. The possibility that anyone, let alone BG, could just bump into Jill accidentally and decide "This is it" is next to none. And there is no evidence he was stalking her.
Then there is question of "why". BG was assaulting women sexually and attempted rape, the problem is JD was not sexually assaulted, nor there was any attempt to rape her. She was coldly executed in a blitz style attack. Whoever did it had only one aim: to kill JD. That does not fit known crimes of BG, at all.
Why would police officers who handle guns be more likely to contaminate BG's jacket with GSR than BG himself, who also handled them? You can't say the GSR was "most probably" the result of cross contamination. It COULD be the result of cross contamination, but it also could have been there because the man who owned the jacket also owned exactly the type of gun used to shoot Jill.
You're attempting to dismiss the available evidence by calling it "dubious," but nobody has ever said the evidence is more than circumstantial. Regardless, the killer still had to match ALL of the known evidence--and out of thousands of people who were investigated, BG was the only one who did. Not because he was the local kook, but because he owned the correct gun, the correct clothing, was seen on the street that morning, had a habit of following women to their door, etc.
Having seen BG's interviews--including his police interviews--he's no fool. Book smart, maybe not. But he's no idiot in my view. His supposed lack of intelligence is regularly used to say he couldn't have done something like this. But what was "this" exactly? Someone walked up to Jill on a quiet morning on a quiet street, had a brief scuffle, pushed her to the ground, shot her, and then walked away. How much evidence would that be expected to leave behind? I would contend not necessarily very much.
BG had committed numerous assaults, but didn't seem to leave behind a huge amount of forensic evidence in any of them. He almost certainly committed at least one rape, yet was only convicted of attempted rape due to a lack of evidence.
BG has always denied things. He still denies it was him in the "mask" photo. He denies owning the gun despite writing it down in his ledger of purchases in his own handwriting. Your idea that he would brag about it because he's a narcissist doesn't actually seem to fit the evidence of BG's typical behavior. Quite the opposite. If anything he seems to be the kind of manipulator who would do something right in front of your face, and afterwards claim you imagined it.
So many of the theories about Jill's death revolve around nobody knowing she was going to be there that morning. Yet many murders really are just a matter of being in the wrong place at the wrong time. Maybe it is unlikely and freakishly unlucky that someone like BG would be randomly walking past Jill's house when she arrived home, and shoot her for no apparent reason. But is that really less likely than some kind of international revenge plot involving hitmen and getaway cars? Personally I don't think so.
You're making the assumption that because Jill was found dead with a gunshot wound to the head, and no other signs of assault beyond some bruising where she was grabbed and forced down, there was no other intent. We simply can't say that one way or the other. What if the killer was trying to rob or assault Jill, shot her during the scuffle, and ran away without completing his original plan? How would anyone, whether us or the police, ever be able to say with absolute certainty?
As it is, BG *was* seen loitering around the street and other nearby streets that morning. He *was* known to wander the streets all day, following random women, trying to strike up conversations with them and generally being a nuisance. He *was* known to follow women to their doorstep. He *was* known to attack women on their doorstep and push them down to the ground. He *was* known to carry weapons and use them in a threatening manner.
The fact that Jill died is the *only* thing that doesn't fit BG's usual M.O. And criminals do escalate their behavior.
