Shortly after the bombing, based on a photo of battery and a battery harness, I had suggested that the Boston Bombers had used RC components for their bombs. Turns out that I was correct. From Fox News:
The bombers who attacked the Boston Marathon last week did not rely on cellphone detonators, but rather toy car speed controllers as the trigger, requiring a clear view of the explosives, according to a national security source familiar with the FBI investigation.
The source, who agreed to discuss progress in the marathon bombing case on the condition of anonymity, said the finding is significant, adding the use of remote-control toy parts as a detonation mechanism is not found in the Al Qaeda online magazine Inspire, which was cited in early reports as the suspects' likely bomb-making guide.NBC reports:
While the working theory among investigators is that one or both of the Tsarnaev brothers triggered the detonation using the speed controllers, Fox News is told a third party in the crowd has not been ruled out, though there is no evidence suggesting a third party at this time. [Docent--What about the Saudi national that was acting suspiciously?]
"I can't comment on any of the specifics on the design of the weapon that went off, but it is very clear when you take the totality of it that there was some outside counsel to these individuals on how to build and how to detonate," Republican Rep. Mike Rogers, chairman of the House Intelligence Committee, said.
Asked about possible third-party involvement, Rogers did not rule it out.
"This was not something that we believe that on their own that they came up with, that design was on their own," he said. "That's why those six months in Russia becomes so important. And other persons of interest that I know investigators would like to talk to becomes very, very important here."
A detailed analysis of the bombs used at the Boston Marathon and during a firefight between the suspects and law enforcement shows how closely the bombmakers followed instructions from the digital al Qaeda magazine “Inspire,” according to a government document obtained by NBC News.
The unclassified report from the Terrorist Explosive Device Analytical Center found that the pipe bombs allegedly thrown from a car by Dzhokhar and Tamerlan Tsarnaev during last Friday’s chase through Watertown, Mass., resembled the design described in “How to Make a Bomb in the Kitchen of Your Mom,” an article in the first issue of the English-language magazine. At least one of the Watertown bombs used an elbow pipe wrapped in black tape, as discussed in “Inspire.”
“The use of elbow pipes specifically is unique,” states the report, “and rare in other extremist and anarchist literature.”
“How to Build a Bomb in the Kitchen of Your Mom” also provided instructions on how to build bombs with kitchen pressure cookers. The bombs detonated at the marathon on April 15 were constructed from pressure cookers, as was a bomb authorities say the suspects threw at police during the Watertown shootout. Tamerlan Tsarnaev, a 26-year-old immigrant of Chechen origin, was killed during the confrontation.
According to the TEDAC analysis, the pressure-cooker bombs also match the “Inspire” designs in their use of spherical shrapnel and gunpowder from fireworks, as well as the possible use of Christmas tree lights as an initiator.
The pipe bombs also used fireworks and spherical shrapnel. Both types of devices apparently used glue to secure the shrapnel, as described in “Inspire.” NBC is not disclosing details that could aid in the construction of a bomb.
Dzhokhar Tsarnaev, who survived the Watertown shootout and was captured last Friday night, has told investigators that he and his brother Tamerlan got bombmaking instructions from “Inspire,” according to law enforcement officials. The TEDAC document, however, notes while the elements of the Boston bombs “use similar components to those described in several issues of ‘Inspire,’” they also diverge from the “Inspire” designs, with different triggers and power sources. A fusing system that used parts from a toy car, say the investigators, does not seem traceable to the magazine.