Brendan Mess, Erik Weissman, and Raphael Teken were all killed by sharp wounds to their neck in 2011. Their bodies were found in a Walktham residence covered with marijuana. Investigators also found $5,000 in cash nearby one of the victims.
Mess had been roommates with Tamerlan Tsarnaev. Both men boxed and trained in martial arts together.
Investigators told ABC News cell phone records show the Tsarnaev brothers were in the area the same day of the murders. The crime remains unsolved but authorities said crime scene forensic evidence links the brothers to the investigation.
Family and friends of the victims say Tamerlan began acting suspiciously strange following the murders. He allegedly never returned to the martial arts gym where the men trained together and also failed to attend his friend's funeral.
Investigators say they don't have enough evidence to charge the surviving Tsarnaev brother for the murders but plan on running more DNA tests.
Tamerlan and his brother Dzhokhar are accused of setting off two shrapnel-packed pressure-cooker bombs near the finish line of the Boston Marathon on April 15. The bombs killed three people and injured approximately 260 others.
Tamerlan Tsarnaev was killed in gunbattle with police in Watertown, Mass. on April 19. The new allegations come days after it was revealed Tamerlan's body was secretly buried at Al-Barzakh Cemetery in Doswell, Virginia Thursday.
His brother, Dzhokhar Tsarnaev, was captured later and remains in custody at the infirmary at Fort Devens federal prison. He faces a potential death sentence if convicted of the terrorism plot.
The brothers are also suspected in the shooting death of an MIT police officer.
ABC News and The Associated Press contributed to this report.
