Investigators examining the Boston Marathon bombings believe the explosions might have been triggered by remote control. -
A radio-controlled or remote-controlled device might have been used to trigger the bombs, according to CBS News, which cited sources.
Brothers Tamerlan and Dzhokhar Tsarnaev are accused of planting the bombs along Boylston Street killing three people and injuring about 260 others. Tamerlan Tsarnaev was killed early Friday in a shootout and chase with police that lasted from Cambridge to Watertown.
The news about the possible trigger comes just days after a federal criminal complaint filed against Dzhokhar Tsarnaev revealed new details about the brothers' movements in the moments before the explosion.
The complaint said that Dzhokhar Tsarnaev is seen in multiple camera and surveillance images using and looking at his phone.
"Approximately 30 seconds before the first explosion, he lifts his phone to his ear as if he is speaking on his cell phone, and keeps it there for approximately 18 seconds. A few seconds after he finishes the call, the large crowd of people around him can be seen reacting to the first explosion," an FBI agent wrote in the complaint.
Authorities have not publicly said what was used to trigger the blasts.
Follow Michael Naughton on Twitter @metrobosmike.