Dzhokhar Tsarnaev admitted his role in the Boston Marathon attacks to the FBI before he was told of his constitutional right to keep quiet and seek a lawyer.
It has been revealed that once Dzhokhar Tsarnaev was read his rights, he immediately stopped talking.
The FBI normally tells suspects they have the right to remain silent before questioning them so all their statements can be used against them in court.
But two anonymous US officials said Dzhokhar Tsarnaev has been questioned by police for 16 hours before he was read his rights.
It is unclear as to whether this will matter in court as the FBI says Dzhokhar Tsarnaev has already confessed to a witness.
A spokeswoman for US Attorney Carmen Ortiz said: “Before being advised of his rights, the 19-year-old suspect told authorities that his older brother, Tamerlan Tsarnaev, 26, only recently had recruited him to be part of the attack.”
The debate over whether suspected terrorists should be read their Miranda rights has become a sticking point.
Many Republicans believe they hinder intelligence gathering.
The Department of Justice has said investigators may wait until they have gathered intelligence about other threats before reading those rights in terrorism cases.
Investigators have found pieces of remote-control equipment among the debris and are analyzing them, officials said.
One official described the detonator as “close-controlled”, meaning it had to be triggered within several blocks of the bombs.
Dzhokhar Tsarnaev is recovering in a hospital from injuries suffered during a getaway attempt last Friday.