Charlie Rowley met with Alexander Yakovenko at the Russian embassy in London.
In the 12 months since the shocking attack, some 250 detectives have worked on the investigation, collecting more than 11,000 hours of CCTV footage and 1,700 statements from the public.
On 4 March 2018, former Russian double agent Sergei Skripal and his daughter were poisoned with a novichok nerve agent in Salisbury. Two Russian nationals, Alexander Petrov and Ruslan Boshirov, were identified as suspects, but an arrest is yet to be made due to protection by Russian extradition laws. It has taken a year for Salisbury to be decontaminated of the poison.
She'd been showing everyone a photograph of Alexander Mishkin.
Your handy guide to what we've learnt so far after a week of stunning revelations.
But the Russian defence is getting thinner and thinner.