Who are Azamat Tazhayakov, Dias Kadyrbayev and Robel Phillipos?

(CNN) -- The number of people potentially embroiled in the Boston Marathon bombings case grew Wednesday to include friends of surviving suspect Dzhokhar Tsarnaev.

Not much is known yet about the three 19-year-old men -- Azamat Tazhayakov, Dias Kadyrbayev and Robel Phillipos.

But here is what CNN has learned so far.

All started at the University of Massachusetts-Dartmouth in 2011, along with Tsarnaev.

Each is accused of removing items from Tsarnaev's dorm room after the April 15 attack, which killed three people and wounded more than 260.

Azamat Tazhayakov

Tazhayakov was already in federal custody before Wednesday on immigration charges. He is from Kazakhstan and had a student visa.

According to the University of Massachusetts-Dartmouth, Tazhayakov is enrolled, but was suspended pending the outcome of the case.

He is charged with obstruction of justice. If found guilty, he could face up to five years in prison and $250,000 in fines.

Harlan Protass, who represents Tazhayakov, said his client "has cooperated fully with the authorities and looks forward to the truth coming out."

Dias Kadyrbayev

Kadyrbayev is likewise a Kazakh national and charged with obstruction of justice.

Similar to Tazhayakov, he could face up to five years in prison and $250,000 in fines if found guilty.

The two men share an apartment in New Bedford, Massachusetts.

Kadyrbayev's lawyer, Robert Stahl, said his client "did not have anything to do" with the bombing and disputed that he tried to block the investigation.

Kadyrbayev was taken into custody along with Tazhayakov last month on suspicion that he had violated the terms of his student visa, according to Stahl.

He said Kadyrbayev was accused of a "technical violation" for failing to attend classes on a regular basis.

Kadyrbayev is not currently enrolled at the University of Massachusetts-Dartmouth.

According to an interview his father gave last week, the 19-year-old "missed a couple, or maybe several classes."

"I can say about my son that he finished school with excellent grades; he was good at math. He helped others. When he saw that help was needed, he always accommodated," Murat Kadyrbayev told Tengi News and STV channel in Kazakhstan.

Robel Phillipos

Unlike Tazhayakov and Kadyrbayev, Phillipos is a U.S. citizen.

Like Kadyrbayev, he is not a current student at the University of Massachusetts-Dartmouth.

Phillipos attended high school with Tsarnaev at Cambridge Rindge and Latin School in Cambridge, Massachusetts, where they both live.

A yearbook photograph shows a smiling Phillipos. Almost directly in front of him, Tsarnaev stares at the camera -- his hand gently resting under his chin.

Phillipos is charged with lying to federal agents investigating the bombing. He faces up to eight years in prison if convicted, along with a $250,000 fine.

A friend described Phillipos as a "good kid."

"He went to school, never got in trouble, took care of his mom," James Turney told CNN affiliate WBZ. "He was not really outgoing, stayed in the house a lot, did homework, got good grades."

Phillipos plays basketball and doesn't have "any anti-American thing about him," Turney said.

"It just doesn't make sense. Robel doesn't have anything to do with this, or what happened, so I don't see why he's being arrested," he told WBZ.

CNN's Matt Smith, Tom Watkins, Susan Candiotti, Deborah Feyerick, Gloria Borger, Carol Cratty, Jake Tapper, Brian Todd, Pamela Brown and Kathleen Johnston contributed to this report.