Friends of accused Boston bomber plead not guilty to obstruction BOSTON (Reuters) - Two college friends of accused Boston Marathon bomber Dzhokhar Tsarnaev pleaded not guilty on Tuesday to charges of obstruction of justice and conspiracy for allegedly removing evidence from Tsarnaev's dormitory room three days after the attack. The two students, who are from Kazakhstan, are accused in federal court of removing a backpack containing fireworks and a laptop computer from Tsarnaev's room at the University of Massachusetts Dartmouth as the Federal Bureau of Investigation was searching for him. Tsarnaev, 20, is accused of setting off a pair of homemade pressure-cooker bombs at the race's crowded finish line on April 15, killing three people and injuring 264 in the largest mass-casualty attack on U.S. soil since the attacks of September 11, 2001. Tsarnaev is also charged in the death of a university police officer from whom he and his brother allegedly tried unsuccessfully to steal a gun. The friends, Dias Kadyrbayev and Azamat Tazhayakov, both 19, are charged with reaching out to Tsarnaev three days after the attack, when the FBI released still images of Dzhokhar and his older brother, Tamerlan, at the site of the bombing. That FBI release - a call for the public's help in identifying the suspects - panicked the Tsarnaev brothers. Their attempt to flee ended in a late-night gunfight with police in the suburb of Watertown on April 18 that left Tamerlan dead. After a day-long manhunt, police found Dzhokhar hiding in a boat parked in the backyard of a home. Prosecutors charged Kadyrbayev and Tazhayakov with removing evidence from Tsarnaev's room in an effort to protect him. They could face 25 years in prison or deportation if convicted. The pair have been in federal custody since May 1, when lesser charges of conspiracy were filed against them. They were indicted on the obstruction-of-justice charges on August 8. A third friend, Robel Phillipos of Cambridge, Massachusetts, is engaged in talks with prosecutors aimed as settling a charge of making false statements in a terrorism investigation. Writing by Scott Malone; Editing by Gary Hill