SIR - The 'evidence' pointing to Russia and President Putin being responsible for the recent nerve agent poisonings in Salisbury seems damning.

All the logic backing up the whys and the wherefores motivating such an attack, also points in this direction.

Yet, it is all circumstantial evidence, and there could yet be another explanation eg organised crime.

Will we ever get definitive proof - a so-called smoking gun - or direct evidence, mainly used to actually convict a guilty person in the courtroom? That remains to be seen. One thing absolutely certain is that this crime was extremely well planned and professionally executed, meaning that the 'smoking gun' may be impossible to find.

David Hornsby, West View Avenue, Wrose