Brendan Mess, Raphael Teken and Erik Weissman were found dead in a Waltham, Mass., apartment with their throats slit and marijuana dumped on their bodies

Tamerlan Tsarnaev, the deceased older brother of the Boston Bombing duo, is now emerging as a possible suspect in a grisly 2011 triple homicide in Waltham, Mass., that took the life of his friend, Brendan Mess, and two others.

“We are looking at a possible connection with the suspect in the marathon atrocity and this active and open homicide in Waltham,” Stephanie Guyotte, a spokeswoman for the Middlesex County District Attorney, told ABC News on Monday.

Mess and Tsarnaev frequently trained together at a local Cambridge gym, as they had the shared ambition of becoming professional mixed martial arts fighters and lived only blocks from one another. The other two victims of the slaying were Raphael Teken, 37, and Erik Weissman, 31. All three men were found with their throats slit and marijuana covering their bodies in an apartment in the Boston suburb. No culprit was ever identified, and the case remains open.

Tsarnaev, 26, died early Friday morning after engaging in a firefight with law enforcement. His surviving brother, Dzhokhar Tsarnaev, 19, was formally charged yesterday with crimes punishable by death. Both brothers are accused of planting pressure cooker bombs near the finish line of the Boston Marathon – a terrorist act that took the lives of three and critically injured over 200.