By Daniel Lovering

BOSTON (Reuters) - A friend of Boston Marathon bombing suspect Dzhokhar Tsarnaev is confident he will beat charges he hampered the investigation into the blasts, one of his attorneys said on Monday citing a "lack of evidence" in the case.

Attorney Matthew Myers said his client, Azamat Tazhayakov, had rejected a deal with prosecutors for a reduced sentence and believes the government's case is "beatable."

"He knows he isn't guilty. He's confident," Myers told reporters outside the federal courthouse in Boston. "I think everybody will be shocked, even just the average juror in Boston will be shocked at the lack of evidence in this case."

Tazhayakov, 20, is one of three of Tsarnaev's college friends accused of hampering the investigation by removing a laptop and backpack containing empty fireworks casings from Tsarnaev's dormitory room at the University of Massachusetts at Dartmouth three days after the attack.

Three people were killed and 264 injured in the bombing at the finish line of the historic race April 15, 2013.

Tazhayakov and Dias Kadyrbayev, a Kazakh exchange student, were charged with obstruction of justice and could face up to 25 years in prison if convicted. The third friend, Robel Phillipos of Cambridge, Massachusetts, faces up to 16 years if convicted of the less serious charge of lying to investigators.

A fourth man, 23-year-old Kyrgyzstan national Khairullozhon Matanov, has separately been accused of lying to investigators and was denied bail on Monday at another hearing.

Kadyrbayev and Tazhayakov were first questioned by investigators four days after the bombing, when heavily armed law enforcement agents arrived at their New Bedford, Massachusetts, apartment. The next day, they were arrested on charges of violating the terms of their student visas.

On Monday, U.S. District Judge Douglas Woodlock said jury selection in Tazhayakov's case would begin on June 30 from a pool of hundreds of potential jurors. He said he expected the trial to begin on July 7.

Defense attorneys contend that statements Tazhayakov made under interrogation were involuntary. Woodlock warned that if he found at trial that the suspect's statements had been involuntary, he would declare a mistrial.

At the Matanov hearing on Monday, Magistrate Judge Marianne Bowler denied bail, saying Matanov was a flight risk. Matanov, a taxi driver who emigrated to the United States in 2010, has been accused of destroying records and making false statements to investigators. He has pleaded not guilty.

Tsarnaev, who also is accused of killing a university police officer in a shootout three days after the bombings, is awaiting trial in a prison west of Boston. He faces the possibility of execution if convicted.

(Corrects date of Tazhayakov trial in paragraph 9)

((Editing by Richard Valdmanis and Jim Loney))