The media theory over the last several days about the Boston Marathon bombing is that the pressure-cooker design came straight off the Internet and didn’t require any specific training. That assumption ignores a couple of key points even if the bomb design matched those readily available on jihadi websites, such as practice and testing, of which so far the FBI has found no evidence in the US. Second, any deviation from those designs would entirely negate that kind of “lone wolf” scenario — and according to the Wall Street Journal, the FBI now believes that Tamerlan Tsarnaev had to have received assistance and/or training for the designs he used:

A Federal Bureau of Investigation analysis of the bombs used in the Boston Marathon attacks has concluded that makers of the devices had some knowledge beyond the step-by-step recipes already described by the surviving suspect in the attack.

Dzhokhar Tsarnaev has told interrogators that he and his brother used bomb-making instructions found in Inspire, an online al Qaeda magazine, according to federal officials. His brother, Tamerlan Tsarnaev, the other accused bomber, was killed during a gunfight with police in Watertown, Mass.