The accused Boston Marathon bomber once called the Sept. 11, 2001, attacks a hoax but showed no signs of extremist views, his college roommate testified on Wednesday.

The roommate, Andrew Dwinells, took the witness stand for a second day of testimony at the trial of Azamat Tazhayakov, a college friend of bombing suspect Dzhokhar Tsarnaev, who has been charged with obstructing the investigation into the April 15, 2013, attack, which killed three people and injured more than 260.

Dwinells, who has largely avoided the spotlight since the bombing, said he recalled Tsarnaev watching a documentary about the Sept. 11 attacks and saying he believed them to be a conspiracy carried out by the U.S. government.

He said the two were not friends and had been randomly assigned to live together at a dorm at the University of Massachusetts at Dartmouth.

Dwinells testified that Tazhayakov, accompanied by two other friends of the bombing suspect, arrived at his room three days after the bombing and said that Tsarnaev had told them to take a few things.

Prosecutors contend that the three, who went to Tsarnaev's room after the FBI released pictures of him at the site of the bombing, took a laptop computer and backpack filled with empty fireworks shells from his room and later dropped the backpack into a dumpster in an attempt to cover up for their friend.

Tazhayakov's attorneys have said their client never touched the laptop or backpack, contending that fellow Kazakh exchange student Dias Kadyrbayev did so.

The three are not charged with any role in the bombing.

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.

Tsarnaev is awaiting trial on charges that carry the death penalty if convicted.

(Writing by Scott Malone; Editing by Eric Walsh and Bill Trott)