Tsarnaev questioned for 16 hours before he was read Miranda rights

Dzhokhar Tsarnaev, suspected of bombing the Boston Marathon with his older brother, Tamerlan Tsarnaev, was questioned for 16 hours by authorities before being read his Miranda rights, the AP reports today.

Tsarnaev, a 19-year-old college student, confessed his role in the crime during the questioning in his hospital room, but that confession may not be admissible in court. Once he was advised of his right to seek counsel and remain silent by a representative from the U.S. attorney's office, the suspect stopped talking.

Police are allowed to question suspects without first Mirandizing them, but then their statements are not admissible in court. If police ask questions that seek to uncover future threats to the public, something called the "public safety exception" provides a loophole to this rule.

So in Tsarnaev's case, if they had asked him if he knew of any planned attacks, or whether there were any bombs planted around Boston, his answers would theoretically be OK to use in a case against him. Authorities questioned both the Christmas Day "underwear bomber" Umar Farouk Abdulmutallab—for 50 minutes—and the attempted Times Square bomber Faisal Shahzad without first reading them their Miranda rights using the public safety exception.

Some Republicans, led by Sen. Lindsey Graham of South Carolina, have argued that Tsarnaev should be treated as an enemy combatant and detained indefinitely so he can be questioned without a lawyer. Since Tsarnaev is a U.S. citizen arrested on U.S. soil—and because authorities have not connected him to a larger terror network—holding him as an enemy combatant most likely would be illegal.

Even if Tsarnaev's reported confession is not allowed to be used in the courtroom, authorities told the AP that the Tsarnaevs told a witness—a man whose car they carjacked—that they were responsible for the bombing. Law enforcement has also uncovered physical evidence from the scene that they think ties the Tsarnaevs to the bombings.