Two college friends of the Boston Marathon bomber were sentenced to prison on Friday for their involvement in protecting their friend Dzhokhar Tsarnaev days after he and his deceased brother detonated two bombs at the 2013 Boston Marathon.

Last year, 22-year-old Azamat Tazhayakov was convicted of obstruction of justice and conspiracy for trying to cover up evidence that could have incriminated Tsarnaev. The Kazakh exchange student was then sentenced on Friday to 3-1/2 years in federal prison for obstructing justice for dumping Tsarnaev's backpack in a dumpster by the off-campus apartment they shared while they were attending the University of Massachusetts Dartmouth.

However, Tazhayakov did not act alone. He was with two other friends -- Dias Kadyrbayev and Robel Phillipos -- when he removed the backpack from the bomber's dorm room amid a massive manhunt three days after the deadly attack.. Inside of the backpack, investigators found empty fireworks shells.

Phillipos, of Cambridge, Massachusetts, was also sentenced on Friday to three years in prison for lying to investigators about the incident.

Earlier in the week, Kadyrbayev of Kazakhstan was sentenced to six years after pleading guilty to obstructing the investigation into the attack.

Both Tazhayakov and Kadyrbayev delivered apology statements before the court for their crimes, but Phillipos opted not to speak since he is planning to appeal of his conviction.

"It just makes me sick what Dzhokhar did on April 15," Tazhayakov told the court while fighting his tears, according to Reuters. "I didn't go there to the dorm room because I made connection that Dzhokhar was some jihadist. I never thought about it. At that moment I saw that one of my friends was alleged bomber and I didn't know if it was true or not."

Tazhayakov went on to say, "I apologize to the people of Boston for what I did. I disappointed a lot of people. I know I can't change what happened, but I've regretted my decision," reports The Boston Globe.