Two days after Plotnikov's death, Tsarnaev flew to Moscow on July 16 last year, and the next day to the US. "It seems that Tamerlan Tsarnaev came to Dagestan with the aim of joining the insurgents," said the source. "It didn't work out. First you need to contact an intermediary, then there is a period of 'quarantine' – before they take someone, the insurgents check him out over several months. "After Nidal and Plotnikov were destroyed and he lost his contacts, Tsarnaev got frightened and fled."