BOSTON (CBS/AP) – The arrest of Boston Marathon bombings suspect Dzhokhar Tsarnaev brought to an end four tense days since twin explosions ripped through the marathon’s crowd at the finish line, killing three people and wounding more than 180.

During a long night of violence Thursday and into Friday, the brothers killed an MIT police officer, severely wounded another lawman during a gun battle and hurled explosives at police in a desperate getaway attempt, authorities said.

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Following his capture, the 19-year-old — whose older brother and alleged accomplice was killed earlier Friday morning in a wild shootout in suburban Boston — was hospitalized in serious condition Saturday, unable to be questioned to determine his motives.

U.S. officials said a special interrogation team for high-value suspects would question him without reading him his Miranda rights, invoking a rare public safety exception triggered by the need to protect police and the public from immediate danger.

The exemption – invoked after the attempted bombing of an airliner on December 25, 2009, along with the attempted Times Square bombing in 2010 – gives officials 48 hours to try and extract information before they are required to read Miranda rights.

Investigators have scoured a Cambridge residence, crime scenes in Boston, Cambridge, and Watertown, and dorm room in the Pine Dale residence hall where Tsarnaev lives in their search for evidence.
From there, U.S. Attorney Carmen Ortiz says a lot of work remains.

“This will continue to be an ongoing and active investigation as we sort all of the details, continue to evaluate a tremendous amount of evidence, and file our formal charges,” she said Friday night.

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President Barack Obama said there are many unanswered questions about the bombings, including whether the two men had help from others. He urged people not to rush judgment about their motivations.

Friday night, the FBI detained three people in New Bedford for questioning in connection with Dzhokhar Tsarnaev. Federal and local agencies also swarmed an apartment complex on Carriage Drive and executed a search warrant.

It was not clear how the three may have been connected to Tsarnaev, but witnesses described them as two college-aged men and a college-aged woman.

Tsarnaev reportedly returned to the nearby UMass Dartmouth campus following the bombings, and one witness told WBZ-TV that a young man taken into custody may have spent time with Tsarnaev on Thursday.

“They said the kid got dropped off by the bomber at 4 p.m. (Thursday) I heard the FBI say,” Joe St. Pierre said.

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