Really, CNN?

(CNN) — The devices used in the Boston Marathon attack Monday are typical of the “lone wolf:” the solo terrorist who builds a bomb on his own by following a widely available formula.

In this case, the formula seems very similar to one that al Qaeda has recommended to its supporters around the world as both crudely effective and difficult to trace. But it is also a recipe that has been adopted by extreme right-wing individuals in the United States.

The threat of the “lone wolf” alarms the intelligence community.

“This is what you worry about the most,” a source with knowledge of the investigation told CNN’s Chief Political Analyst Gloria Borger. “No trail, no intelligence.”

Officials have told CNN that among the materials used in the attack on the marathon were some sort of timing device, a basic mixture of explosives and some sort of metal container containing nails and other projectiles. The FBI said late Tuesday that what appeared to be fragments of ball bearings, or BBs, and nails had been recovered and had possibly been contained in a pressure cooker. […]

Such a formula is certainly not unique to AQAP. Variations appear all over the Internet. A senior U.S. counterterrorism investigator told CNN that pressure cooker bombs have also been a signature of extreme right-wing individuals in the United States who he said tend to revel in building homemade bombs.