As US investigators attempt to piece together the motivations that led Tamerlan and Dzhokhar Tsarnaev to bomb the Boston Marathon, attention is turning to the six-month stint that Tamerlan spent in Russia in 2012.
Tamerlan stayed with his father in Makhachkala, the capital of Dagestan, the republic in southern Russia that borders the family's ancestral homeland, Chechnya.
While there is no evidence yet that the brothers were inspired by Chechen terror movements, or even by Islamist ideals, the fact that Tamerlan spent half a year in Makhachkala, the most restive city in Russia, raises questions.
As Chechnya has become more stable under the iron rule of pro-Kremlin leader Ramzan Kadyrov, its neighbour Dagestan has seen a low-grade civil war bubble away in recent years.
Dagestan's Interior Ministry has said that neither brother had been in the republic for several years, but this contradicts the testimony of several relatives and neighbours who say Tamerlan was there last year.
Members of the Tsarnaev family, while admitting that Tamerlan spent six months with his father in Dagestan, denied he had contact with the rebels there.
His father has claimed that Tamerlan socialised little, while his aunt said Tamerlan seemed "more American" than Chechen and "didn't fit into the Islamic world".
But the Islamist insurgency in Dagestan is complex. It blends in with criminal networks, which also have tangled links with the administration itself, and it is always difficult to understand who has what sympathies or connections.
Tamerlan would not have had to attend a jihadi training camp to have come into contact with extremists.
Dagestan's leading terrorist grouping has distanced itself from the brothers in a statement.
The group, part of a network led by Doku Umarov -- the Chechen terror leader who claimed responsibility for a suicide bomber who killed 35 people at a Moscow airport in 2011 -- said it was not engaged in operations in the US and was battling solely against Russia.
In a separate development last night, it emerged that investigators in a Boston suburb are looking into whether there are links between Tamerlan and an unsolved 2011 slaying.
Tamerlan, who was pronounced dead early Friday after a shootout with police, was a friend of one of three men found dead in an apartment on September 12, 2011, with their necks slit and their bodies reportedly covered with marijuana. Tsarnaev's friend, Brendan Mess, was also a boxer.
Middlesex County District Attorney's Office spokeswoman Mary Beth Long said that authorities would check for any connections between the murder and Tamerlan. She claimed that it's customary to look for connections between new crimes and unsolved ones.
(© Independent News Service)