One person who worked with Sergei Skripal in Russia's foreign spy agency when the double agent was based in Moscow is retired colonel Vladimir Koshelev .
Speaking to Euronews, he dismissed the idea that the Kremlin could have been involved in the Salisbury attack.
''We should not to exclude the possibility of another state's participation but which state, that's the big question. Possibly Britain's secret services decided to make use of their former spy, on the other hand it's also possible that, what we might call, a "friendly" secret service took part in this. This is just one possible scenario. I'd like to point out, why not another country which used to be part of the Soviet Union, where there are warehouses with these types of weapons, for instance Ukraine"
(N.B. Novichok was known to be produced in the Soviet era in Uzbekistan)
"In addition, do not exclude the possibility that this nerve agent, Novichok, could have fallen into criminal hands," continues Koshelev.
"If there really was a serious threat to Mr. Skripal's life, why didn't he folllow a witness protection programme? Moreover, he lived openly. He lived under his own name and surname. His daughter moved back and forth freely from Britain to Russia, as did his son. There were no threats in this regard and suddenly this happens. Unfortunately, there are and always will be traitors. There are traitors from our country who have fled to the US and Israel, but why do they only get poisoned and perish in Britain!. This raises certain questions. Why just in Britain?"