Left, Dzhokhar Tsarnaev, suspect in the Boston Marathon bombings. Right,...

Left, Dzhokhar Tsarnaev, suspect in the Boston Marathon bombings. Right, an image from Twitter user Andrew Kitzenberg, who said he witnessed the suspects' firefight with police in Watertown, Mass. (April 19, 2013) Credit: FBI, Andrew Kitzenberg

BOSTON -- The flow of information from a hospitalized terror suspect to FBI interrogators stopped abruptly Monday after a federal magistrate at a bedside proceeding read him his Miranda rights, according to sources familiar with the investigation.

For the prior 16 hours the interrogators had been grilling the wounded suspect, accused Boston Marathon bomber Dzhokhar Tsarnaev, charged Sunday with using a weapon of mass destruction and malicious property damage. They were questioning him under a narrow public-safety exception to the rights that arresting authorities must read to arrestees under the landmark 1966 Supreme Court precedent.

One of the sources lamented that valuable intelligence may have been lost because Tsarnaev, 19, stopped cooperating after the warnings by the magistrate, Judge Marianne B. Bowler.

The incident reignited the debate, kindled after the 9/11 attacks, over how to treat terrorism suspects in a democracy. The public safety exception, which permits authorities to delay the Miranda warning, was carved out by the Supreme Court two decades after Miranda in a case over police questioning of a rapist about a missing gun. It was used by authorities successfully in 2009 to interrogate underwear bomber Umar Farouk Abdulmutallab and in 2010 with failed Times Square bomber Faisal Shahzad.

The source said investigators believed they had up to 48 hours to question Tsarnaev before he received the warnings.

Rep. Peter King (R-Seaford) assailed the magistrate's actions. "This was such a productive interrogation, and so much information was coming out," he said.

Among the revelations Tsarnaev made before the warning, a source said: He and his accused accomplice, his now-dead brother, Tamerlan, acted alone, planned to next attack Times Square and were inspired by online al-Qaida propaganda.

Thursday, acting court clerk Robert Farrell said: "The court has no comment on this issue." But a person familiar with the magistrate's thinking, speaking anonymously, said she convened court because "as soon as someone is charged, they're supposed to be seen without unnecessary delay."

"We see people without undue delay whether it's a felon in possession of a firearm" or an accused terrorist, the source said.

He noted Bowler signed the complaint the night before the bedside proceeding.

Tsarnaev spoke one word to the court. He said, "No" -- when asked if he could afford an attorney. "Let the record reflect that I believe the defendant has said, 'No,' " Bowler said.

The defendant, a source said, hasn't spoken to interrogators since.

Latest videos