British authorities charged Boshirov and Petrov with the March poisoning of Skripal and his daughter in which they were attacked with the nerve agent novichok, which officials say was spread on a door knob to their home in Salisbury.
Mishkin had travelled to the United Kingdom under the name of Alexander Petrov.
One of the two suspects in the poisoning of an ex-spy in England is a doctor who works for Russian military intelligence and travelled to Britain under an alias, investigative group Bellingcat reported Monday.
We have now identified "Alexander Petrov" to be in fact Dr. Alexander Yevgenyevich Mishkin, a trained military doctor in the employ of the GRU.
British Prime Minister Theresa May said the attack was likely ordered at the highest levels of the Russia government, an allegation vehemently rejected by Russian President Vladimir Putin. While recent failings by the GRU had made it easy to mock the spy agency, he said, it would be foolish not to take them seriously.
Russia has denied any involvement in the case and has claimed the two Russians were in Salisbury on a tourist trip.
The interview was not only widely mocked but also left security analysts at a loss to explain why Russian Federation would stage-manage their hapless TV appearance in the first place.
British police said they would not comment on speculation about the real identities of the two men facing charges, in response to a query about the latest report.
The poison used, according to British authorities, was novichok, an especially unsafe nerve agent, and, analysts say, it was nearly certainly Mishkin's role to apply the poison, which is thought to have been smeared on the handle of Skripal's front-door. The British woman, Dawn Sturgess, died after unwittingly spraying the novichok on her wrists.More news: Intel's 9th generation processors are here to outperform the competition
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The second suspect in the attempted poisoning of a former Russian secret agent has been identified by an investigative website.
The case prompted the biggest East-West diplomatic expulsions since the Cold War.
"Until early September 2014, Mishkin's registered home address in Moscow was Khoroshevskoe Shosse 76B - the address of the headquarters of the GRU", Bellingcat's investigation concluded.
Bellingcat cross-referenced this information with other leaked databases, including a vehicle insurance database which identified the same man as the driver of a Volvo registered to the GRU headquarters.
The website claimed Mishkin travelled extensively from 2011 to 2018 on a fake identity.
The full report, presented by two Bellingcat reporters at Westminster on Tuesday, explained how they had pieced together evidence of the man's identity from scraps of information on the internet, via leaked official databases and using a copy of personal documents, including passport dossiers.
He had climbed the ranks of the GRU after graduating from the a military medical academy no later than 2001, and relocated to Moscow at some point between 2007 and 2010.
Last week, the Justice Department filed criminal charges against seven members of the GRU, accusing them of hacking into the U.S. Anti-Doping Agency in Colorado Springs, Colorado, as well as four global sports governing bodies.