Fox News’ Catherine Herridge is reporting today that the FBI has not ruled out the possibility of a third party involved in the Boston Marathon terrorist bombing. Evidence that the two bombs were detonated not by a cell phone but by parts ripped from a toy car remote control suggest that whoever triggered the explosions had to have been in the line of sight of the bombs.

Further, the instructions the Tsarnaev brothers were believed to have followed to construct the pressure cooker bombs didn’t mention the remote control method of detonation, though a search of their computers might turn up a source for that information.