The "terrorism experts" are pretty much always wrong. They thought that the World Trade Center truck bombing must have been done by Serbians, they thought that the Oklahoma City bombing was the work of Arabs----one of them said that the bombers were trying to cause the maximum number of casualties, which he said was "a middle eastern trait". Turned out to be an American trait.
For the Boston Marathon bombing, they figured it was right-wingers--violent tea baggers. The bombing was on tax day, and it was Patriots Day and it was in the city where the Boston Tea Party happened.
Hell, maybe the young fellows who did this were tea partiers. It would still make more sense than them doing it because they were Chechens.
The Czech Republic has issued a statement explaining that Chechnya and the Czech Republic are two different places.