Federal prosecutors say the Boston Marathon bombing suspects used "relatively sophisticated" bombs with fuses made from Christmas lights and remote-control detonators made from model car parts.
A court filing by prosecutors Wednesday argues against a defense motion to throw out suspect Dzhokhar Tsarnaev's statements to FBI agents because he was questioned without a lawyer.
Prosecutors say the bombs, comments Tsarnaev and his brother made to a carjacking victim that they might explode more bombs in New York and a note Tsarnaev wrote in a boat where he was captured made it imperative to know if there was a continuing terror threat before informing him of his rights, an allowed exception.
They say Tsarnaev said he and his brother acted alone and there were no more bombs.
Tsarnaev has pleaded not guilty. His brother was killed.