BOSTON — Robel K. Phillipos, the former University of Massachusetts at Dartmouth student who is accused of lying to the authorities investigating the Boston Marathon bombings, will seek to be released from federal custody on Monday, his lawyers said in court papers filed over the weekend.

The lawyers said that Mr. Phillipos, 19, had nothing to do with the bombings and was frightened and confused when he was interrogated about going with two other friends to the college dorm room of Dzhokhar Tsarnaev, one of the two chief suspects in the case, and removing a backpack and fireworks that the investigators consider to be evidence. The other suspect, Mr. Tsarnaev’s older brother, Tamerlan, 26, died after a shootout with the police.

As Washington gears up this week for its first hearings on the Boston Marathon bombings, Representative Peter T. King, Republican of New York, said Sunday that he believed the brothers did not act alone.

“It’s very difficult to believe that these two could have carried out this level of attack with this level of sophistication and precision acting by themselves, either without training from overseas or having at least facilitators here at home,” Mr. King, a former chairman of the House Committee on Homeland Security, said on the CNN program “State of the Union.”