Forensic evidence may link the Tsarnaev brothers to their possible involvement in a 2011 unsolved triple murder in Waltham, Mass., two years before the brothers would become suspects in the Boston Marathon bombings.

Ever since Tamerlan, 26, and Dzhokhar, 19, Tsarnaev were identified as the men believed to have carried out the Boston attacks, the prosecutors’ office in Middlesex County, Mass., has been investigating the possibility that the older brother was behind the fatal stabbings of Brendan Mess, Erik Weissman and Raphael Teken in Waltham.

Now, the prosecutors’ office is also looking into whether both Tamerlan and Dzhokhar committed the unsolved murders, according to ABC News, which reported that “mounting evidence” buoyed by “forensic hits” make the brothers strong suspects.

The kilings of Mess, Weissman and Teken have gone unsolved since their gruesome murders on Sept. 11, 2011. At the time, the Middlesex County District Attorney’s Office said it believed the three men knew their killer or killers.

Tamerlan identified Mess as his “best friend” to the owner of the martial arts gym where he and Mess worked out, according to the Boston Globe.

Attention turned to him after family and friends of the victims in the Waltham murders saw pictures of him after the bombings and recalled how he did not attend Mess’ funeral and stopped making appearances at the gym, ABC News reports.

The three victims ordered food from Gerry’s Italian Kitchen, but a deliverywoman heard no answer from inside the apartment when she rang the bell around 8:45 p.m. on Sept. 11, 2011.

The restaurant drew the attention of authorities nine days after the Boston bombings after empty fireworks with the gunpowder taken out were found in a charity bin located in Gerry’s parking lot, ABC News reports.

Residents of Waltham and nearby Watertown, Mass., told the network that they remember Tamerlan delivering food and that he and his brother worked as pizza deliverymen. But the restaurant denied that either brother worked for Gerry’s.

The Middlesex County District Attorney’s Office said late last month that it was looking into the possibility that Tamerlan was involved in the triple homicide.

"We are definitely going to pursue any new leads," spokeswoman Stephanie Guyotte said.

News that the Tsarnaev brothers are strong suspects in the Waltham triple murders comes the same day it was revealed Tamerlan had been buried in Virginia.

He died in a firefight with authorities April 19, four days after the Boston bombings. His brother escaped but was captured later that same day by federal and state authorities in Watertown, where Dzhokhar was found hiding in a boat in the backyard of a home.

Dzhokhar faces two terrorism-related charges in connection with the bombings, which killed three people. He has yet to be charged in the murder of MIT police officer Sean Collier, who was allegedly killed by the brothers shortly before the firefight with authorities on April 18.