A college friend of marathon bomber Dzhokhar Tsarnaev was sentenced Friday to three and a half years in prison after he tearfully apologized to the residents of Boston for impeding the investigation into the 2013 attack while authorities frantically searched for the suspects.

Azamat Tazhayakov was convicted of conspiracy and obstruction of justice for removing Tsarnaev’s backpack from his dorm room at the University of Massachusetts-Dartmouth with another friend. The backpack contained fireworks that had been emptied of their explosive powder.

“There is no question that this was a very serious offense – the failure to act properly when confronted with the devastating event,” judge Douglas Woodlock said.

Tazhayakov denounced Tsarnaev’s actions Friday before he was sentenced, saying the decision to bomb the marathon made him sick. Tazhayakov’s father wept in the courtroom as his son apologized for what he had done.

Prosecutors had recommended a four-year sentence for Tazhayakov. His lawyer asked the judge to sentence him to time served for the 26 months he’s already spent in custody.

Another college friend of Tsarnaev’s is due to be sentenced Friday afternoon.

Robel Phillipos was convicted of lying to the FBI days after the bombings. Former Massachusetts governor Michael Dukakis, a friend of Phillipos’s family, wrote a letter of support for him and even testified during his trial.

In the letter to the judge, Dukakis wrote that he “can’t understand why justice would be served by incarcerating him”.

Prosecutors said Friday that they are seeking a sentence of a little over five years for Phillipos.

A third friend of Tsarnaev’s was sentenced Tuesday to six years in prison for not calling police when he recognized photos of Tsarnaev as a suspect.

Dias Kadyrbayev pleaded guilty last year to obstruction of justice and conspiracy charges for removing items from Tsarnaev’s dorm room after recognizing his friend in photos released by the FBI days after the bombing.

Three people were killed and more than 260 were injured in the 2013 bombing. Tsarnaev, 21, has been condemned to death by a federal jury and is awaiting formal sentencing 24 June.

Prosecutors say there is no evidence any of the friends knew of plans by Tsarnaev and his older brother to bomb the marathon. Tamerlan Tsarnaev, 26, died after a shootout with police days after the bombings.