I very much doubt it. It's murder. Plain and simple. He was tortured for 3 years. He was denied medical care. If it was a blood clot he didn't have to die from it if he was given medical care.
There's some of the follow-up comments that are saying the translation is a little off, so it should be more like 'all we have been told' or 'for all that we know' in the sense of there being the official story which may have some basis in fact but being an official report from the Russian authorities there will be not even the slightest mention of the possibility of the trigger for that cause of death.
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[ the below posted separately a bit later but auto-appended to the above ]
It just gets worse. I'm so shocked by this. I know I shouldn't be, but god this is mad. He was so close to being free. It's the exchange news that's shocked me, not Putin killing him because of it.
I'd be tempted to suggest this was a stalling tactic rather than genuine progress - that said, if it was for real then it may heve been a sign of Russia having a particular need of that particular arms dealer.
There's been numerous posts (obvs with a 'tbc' caveat) Russia having trouble with various aspects of weapons (and weapons related) procurement, or maybe they need access to money because the central Russian banks are running out of gold since there's a lot less people accepting roubles these days.
Also fun, recently noted that about a third of loans in Russian banks are to Chinese companies though that was on Tass and possibly Interestingly I don't recall any opinion offered as to whether it was a good thing or a danger to the Russian economy.
(just the small sections that we see of lots of interconnected chains, one of the reasons Putin likes the 'multipolar world' not because of ideas of fairness but it gives him more sides to play against each other)