Russian opposition politician, Boris Nemtsov, was shadowed by an agent linked to a political assassination team for almost a year before he was shot dead, an investigation has found.
Nemtsov was a fierce adversary of President Vladimir Putin. His murder in 2015 is the highest-profile political killing since Putin came to power.
The authorities deny any involvement.
Bellingcat, The Insider and the BBC found evidence that Nemtsov was shadowed on 13 trips before his murder.
Boris Nemtsov rose to prominence in the 1990s, served as deputy prime minister under President BorisYeltsin, and was widely tipped to be Yeltsin’s successor.
Instead, Mr Putin came to power and Mr Nemtsov was pushed to the margins of Russian politics. He became an effective campaigner, exposing corruption and denouncing Russia’s 2014 attack on eastern Ukraine.
On February 27, 2015, Mr Nemtsov was shot dead just yards from the Kremlin, and just days before he was due to lead a protest against the war.
Five men of Chechen origin were quickly arrested and later jailed for his murder. But the official investigation left the most urgent questions unanswered: who ordered the killing and why?
Seven years later, the BBC – working with the investigative websites, Bellingcat and The Insider – revealed evidence that in the months running up to the killing, Nemtsov was being followed across Russia by a government agent linked to a secret assassination squad.
Using leaked train and flight reservation data, the investigation shows that Mr Nemtsov was followed on at least 13 journeys.
The last time the agent followed Mr Nemtsov was on February17, 2015, just 10 days before the assassination.
According to his documents, the agent’s name is Valery Sukharev. All the evidence suggested that at the time, he served with the FSB, Russia’s main security agency. One of the mandates of the FSB is to manage internal political threats on behalf of the Kremlin, including monitoring movements of people across the country.
All flight and train reservations are recorded in an FSB database called Magistral. But the database not only captures the movements of people Russian agents might want to track, it can also be used to reveal the movements of the agents themselves – people like Mr Sukharev. -BBC