(Updates with testimony of Tsarnaev roommate)
By Scott Malone
BOSTON, July 8 (Reuters) - A friend of the Boston Marathon bombing suspect told an FBI agent that he and two friends removed a backpack containing empty fireworks shells from the suspected bomber's dorm room out of a desire to protect him, the agent testified on Tuesday.
Sara Wood of the Federal Bureau of Investigation testified that the friend, Azamat Tazhayakov, three times denied knowing what was in the backpack before admitting what he and his friends had found in bombing suspect Dzhokhar Tsarnaev's dorm room at the University of Massachusetts at Dartmouth.
Tazhayakov, 20, is the first of three Tsarnaev friends to be tried on charges of interfering with the investigation of the April 15, 2014, blasts, which killed thee people and injured 264. He has pleaded not guilty and his attorney on Monday said Tazhakayov's roommate and fellow Kazakh exchange student Dias Kadyrbayev was responsible for taking the fireworks casings, from which the gunpowder had been removed.
"He stated that he believed Dias took the fireworks trying to defend Dzhokhar," said Wood, who interviewed Tazhayakov on April 19, 2013, four days after the bombing.
The three friends are charged with removing evidence from Tsarnaev's room shortly after the FBI on April 18 released photos of Tsarnaev and his older brother, who it said were suspected in the attack but had not yet identified.
Tsarnaev's roommate, Andrew Dwinells, also testified, saying he was assigned randomly to live with Tsarnaev and that they were never close. He said he let the three men search through Tsarnaev's things but was puzzled by the experience and texted his roommate to ask about it afterward.
"This was a little abnormal," he said.
The morning after the search, after the brothers had been identified, Tazhayakov and Kadyrbayev decided to throw away the backpack, Wood testified that Tazhayakov told her.
"The defendant said that Dias stated, 'We should throw out the backpack with the fireworks,' and the defendant stated, 'I agree,'" Wood said.
Defense attorneys are seeking to show that Tazhayakov's statements to the FBI after being ordered out of his home by heavily armed agents and taken in handcuffs to a police station but not arrested were not voluntary, which would make them inadmissible.
Wood testified that Tazhayakov fell asleep at one point during their interview, which ran into the early morning hours the next day, and that Tazhayakov had been asked to sign a form advising him of his rights before he was allowed access to a bathroom.
Tazhayakov could face up to 25 years in prison if convicted of obstruction of justice and conspiracy. Kadyrbayev faces the same charges, while a third friend, Robel Phillipos, is accused of the lesser charge of lying to investigators. The other two men face trial in the fall.
None of the three men have been accused of a role in planning the bombing, which prosecutors contend was the work of Tsarnaev and his brother, Tamerlan, who died after a gun battle with police on the night of April 18, 2013.
Dzhokhar Tsarnaev is awaiting trial on charges that carry the death penalty if convicted. (Editing by Bill Trott)