Three college friends of accused Boston Marathon bomber Dzhokhar Tsarnaev have pleaded not guilty to charges that they helped cover his tracks when the FBI was trying to find the people responsible for the 15 April attack.
All three are charged with removing a laptop and a backpack containing empty fireworks shells from Mr Tsarnaev's room three days after receiving a text message from him telling them to "go to my room and take what's there," according to court papers.
Dias Kadyrbayev and Azamat Tazhayakov, both from Kazakhstan, pleaded not guilty to the charge of obstruction of justice and could face 25 years in prison or deportation.
Robel Phillipos, of Cambridge, Massachusetts, pleaded not guilty to charges of lying to investigators and could face up to 16 years in prison.
None of the men is charged with involvement in the bombing. Prosecutors said they planned to present about 20 witnesses in a trial they estimated would take two weeks.
After the hearing, Mr Phillipos – who is under house arrest - was surrounded by a group of supporters and left court without speaking to the media.
Federal prosecutors said that Dzhokhar Tsarnaev, now 20, and his older brother, Tamerlan, killed three people and injured 264 other with a pair of homemade pressure-cooker bombs at the crowded finish line of the marathon on 15 April.
Three days later, after the FBI released pictures of the duo, then known only as suspects 1 and 2, standing near the finish line and asked the public for help in identifying them.
That night, after communicating with the younger Tsarnaev via text message, the three accused allegedly entered Mr Tsarnaev's room and removed evidence, prosecutors said.Mr Kadyrbayev and Mr Tazhayakov later threw out the backpack, while Mr Phillipos lied about his involvement, prosecutors said.
Mr Kadyrbayev's attorney said his client had not intended to obstruct justice and did not understand what Mr Tsarnaev had done.
"There was no criminal intent from him to help Dzhokhar, no obstruction of justice in any way," attorney Robert Stahl told reporters after the hearing.
The two Tsarnaevs later that night went on to shoot and kill a university police officer, prosecutors charge, before engaging in a gun battle with police in Watertown, Massachusetts, that ended when Dzhokhar fled, running over his 26-year-old brother in the process.
Tamerlan Tsarnaev died of his injuries, while Dzhokhar evaded arrest for most of a day, leading to a lockdown of much of the greater Boston area. Dzhokhar, badly wounded, was found hiding in a boat in a backyard the evening of 19 April.
He has been charged with crimes that carry the possibility of the death penalty.