It’s been more than a year and a half since police found three men murdered inside a Waltham apartment with their throats slit and marijuana sprinkled on their bodies. But authorities believe they may have new leads on the investigation because Tamerlan Tsarnaev, the suspected Marathon bomber, was close friends with one of the victims.

On Sept. 12, 2011 detectives discovered the bodies and began an investigation into the murder of Brendan Mess, 25, of Waltham; Erik Weissman, 31, of Cambridge; and Raphael Teken, 37, of Cambridge, who graduated from Brandeis in 1998 and majored in history. The three men were found inside an apartment on Harding Avenue off of Main Street.

The Boston Globe reported on Saturday that Tsarnaev was close with Mess, and once introduced him to the owner of a local gym as his “best friend.”

A spokeswoman for Middlesex District Attorney Marian Ryan said the investigation remains ongoing.

“We continue to follow all leads,” Stephanie Guyotte said, adding that the office will pursue any new information that comes to light in the investigation of the Marathon bombing.

At the time, the murders shocked the quiet residential street, and families gathered behind police tape as officials from the District Attorney’s Office began their investigation.

That night, former Middlesex District Attorney Gerry Leone described the apartment as a “very graphic crime scene.” Leone later released a statement saying that “based on the present state of the investigation, it is believed that the victims knew the assailant or assailants, and the attacks were not random.”