They were Chechnyan, which would explain why Putin would offer help. And the brother who is still alive is believed to be somewhere between the Watertown Mall and Mt. Auburn Street, which has a very large Armenian population as well as many Eastern European immigrants. I used to work in Watertown, which is still under lockdown, as well as a number of close sub-burbs like Newton & Belmont. I work a few miles north of it near an air force base which is eerily quiet for a Friday.
We can get around, but friends in those towns can't even go get beer!
-John