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.

Support for GBH is provided by:

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.