Sergei Skripal was a colonel in Russia's Military Intelligence Service (GRU), who was arrested and convicted of high treason in Russia in 2006, and sentenced to 13 years in prison. According to the prosecution, he had spied for the United Kingdom's MI6 as a double agent. After the prisoner exchange in 2010 he moved to the UK and in 2018 Skripal and his daughter Yulia were poisoned with a nerve agent in Salisbury, England. Three unrelated people were accidentally poisoned as well, one of them fatally.