A high-ranking Russian military intelligence service officer who was reportedly in Britain during the Salisbury Novichok attack has been named as Denis Sergeev.
The investigative website Bellingcat said the 45-year-old member of the GRU, who uses the alias Sergei Fedotov, arrived in Britain on the same day as the two suspected attackers, 48 hours before the poisoning.
Bellingcat said it is unclear what role Mr Sergeev may have had, if any, in the Salisbury nerve agent attack, which saw the use of a military grade toxin to target a former Russian double agent, in March last year.
The attempted assassination of Sergei Skripal left him and his daughter Yulia critically ill, and resulted in the death of Dawn Sturgess in July.
Two Russian nationals have been accused of travelling to the UK to try to murder Mr Skripal with Novichok, smearing the highly-toxic substance on the door handle of his home.
A counterfeit Nina Ricci perfume bottle is thought to have contained the substance, and is what Ms Sturgess handled.
She subsequently fell ill in Amesbury, Wiltshire, and died after exposure.
Evidence gathered by intelligence agencies led the Government to conclude that two the men were officers from the Russian military intelligence service, the GRU.
The two suspects, known by their aliases Alexander Petrov and Ruslan Boshirov, were caught on CCTV in Salisbury the day before the attack.
During an interview on Russian state-funded news channel RT, Mr Boshirov said they had travelled to Salisbury to see the “wonderful” city of Salisbury and the “famous” spire of the cathedral.
The real identities of both men were also revealed by Bellingcat, with Dr Alexander Mishkin using the alias Petrov, and Mr Boshirov named as Colonel Anatoliy Chepiga.
According to the website, over the past couple of months the Russian authorities have begun deleting any public records of Mr Sergeev, Mr Chepiga and Mr Mishkin.
Bellingcat said it jointly investigated over a four-month period with The Insider, of Russia, and the Czech Respekt, with Finnish newspaper Helsingin Sanomat also contributing.
The website states that Mr Sergeev was born in Kazakhstan during the Soviet Union era.
It said he served in the Russian army and was transferred to Moscow to enrol at the Military Diplomatic Academy, known as the GRU Conservatory, sometime between 2000 and 2002.
“We have not established what Denis Sergeev’s service prior to the academy involved; however, is known that recruitment into the academy takes place among military officers with the minimum rank of captain who have excelled at their military service, traditionally in Spetsnaz or navy units,” Bellingcat states.
“Like all other graduates, Sergeev would have finished the academy with a minimum rank of lieutenant-colonel.
“While we have no confirmation of his current military rank, the time served and the nature of his assignments since graduation indicate he currently holds a minimum rank of full colonel, and possibly major-general.”
The investigative group found his Fedotov alter ego was created in 2010, and it tracked the travel movements of this name between 2012-2018.
Bellingcat said Mr Sergeev, who has a wife and adult daughter, flew to London on March 2.
He left Moscow at 7am on the SU 2580 Aeroflot flight, with Mr Mishkin and Mr Chepiga arriving on a flight later that day.
He had been due to fly back on a return flight with the same company on March 4, but never boarded it and somehow made his way to Rome and boarded a flight to Moscow that day, the group said.
“It is unclear what Fedotov’s (Sergeev) role may have been, if any, in the preparation and execution of the poisoning operation,” Bellingcat said.
“We could also not establish if he travelled to Salisbury on any of the days he was in the UK.”
Bellingcat has also previously reported that Fedotov had travelled to Bulgaria in April 2015, just a few days before Bulgarian businessman Emilian Gebrev was poisoned by an unidentified substance.