We have a (EDIT - silly me he's not dead) nearly dead body, so a crime has clearly been committed. We have in the courts a sophisticated process for determining whodunnit and what they done with a high standard of evidence.

Given that the people accused of undertaking the killing are foreign state actors, that process is unlikely to be taken to conclusion. The situation is political, and the people who are publicising the information are closely involved with people who are hired to be _professionally untrustworthy_.

We don't have any evidence, and should judge the situation by what the response is. If it is understated and a censure of the Russians, the UK secret service are probably being truthful. If it ties in to some real action (ie, is used as justification for something that wouldn't otherwise make sense) then the UK secret service were probably lying. It isn't like the Russians would have revealed any new intent or capability with this incident.

This type of analysis is sorely lacking in the "which side are you on" comment. We should not lock in behind a western government doing something bad because they are pointing fingers at Russia. We've regretted doing that in the past - WMD and Saddam is a pretty cut and dried example (I have others, but they aren't as clear cut and a lot of people might not regret them).