Probably they used his smarts to build the Pressure Cooker bombs and what else ? What did they teach this young Chechen Muslim Jihadist in Boston ? What classes did he take ?
He and the brother lived in the same locale as the 9/11 terrorists.
And there are cells all over the US. We do NOT know all the situations/attacks that have been avoided.
There are at least 8 mosques in Boston.