Authorities investigating the Boston Marathon bombing have concluded that the bombs mostly likely relied on components from remote-controlled toy cars for the detonation mechanism, according to a bulletin from the FBI and Homeland Security Department.

Fox News has learned that the bulletin, sent Monday night to update local, state and federal law enforcement, is based on new forensic analysis of the bombs and reads in part, “each device likely incorporated an electric fusing system using components from remote controlled toy cars, such as a transmitter and receiver pair operating at 2.4 GigaHertz, and an electric speed controller used as a switch mechanism and sub-c rechargeable battery packs as power source."

House Homeland Security Committee Mike McCaul, who has been briefed on the bombing investigation, told Fox News the new information is further confirmation the two bombs were not made by amateurs.

“This transmitter that was used out of a toy car, that's a very sophisticated pressure cooker bomb that you don't see every day," McCaul said. "My judgment is they had training performed by either an individual or individuals who are still at large.”

Fox News is told the bulletin also concludes that the two bombs were not identical, as the early reporting suggested. One bomb contained bb’s and nails for shrapnel, while the other only contained nails.

Jonathan Gilliam, a former member of the FBI’s New York Joint Terrorism Task Force and former Navy SEAL, told Fox News that the quantity and effectiveness of the devices also suggested formal, hands-on training, not expertise that could be gleaned from online Al Qaeda instruction manuals like “Inspire” magazine.

“If you look in a book and try to construct something, you can make an object. But when you add in explosives to it and you don't know how those explosives should be handled, you're setting yourself up for a lost hand or even life," Gilliam explained.

Fox News was told the type of explosive was listed in the bulletin as a “blend” containing “nitrate and perchlorate-based oxidizers,” which Gilliam added was consistent with fireworks explosives. Fox News confirmed Monday that Tamerlan Tsarnaev bought fireworks on Feb. 6 in New Hampshire and asked for the most powerful and loudest available.

Fox News correspondent Catherine Herridge's book "The Next Wave: On the Hunt for al Qaeda's American Recruits" predicted in 2011 the rise of homegrown terrorism, laid out the profile of the new generation of al Qaeda inspired American recruits and explained the role of social media in the new digital jihad.