WALTHAM, Mass. -- Investigators in a Boston suburb are looking into whether there are links between a suspect in last week's Boston Marathon bombing and an unsolved 2011 slaying.

Marathon bombing suspect Tamerlan Tsarnaev, who was pronounced dead early Friday after a shootout with police, was a friend of one of three men found dead in an apartment in Waltham on Sept. 12, 2011, with their necks slit and their bodies reportedly covered with marijuana.

Tsarnaev's friend, Brendan Mess, was also a boxer.

Middlesex County District Attorney's Office spokeswoman MaryBeth Long told The Associated Press on Monday that authorities would check for any connections between the murder and Tsarnaev.

She says it's customary to look for connections between new crimes and unsolved ones.

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  • Azamat Tazhayakov, Dias Kadyrbayev, Dzhokhar Tsarnaev

    This undated photo added on April 18, 2013 to the VK page of Dias Kadyrbayev shows, from left, Azamat Tazhayakov and Dias Kadyrbayev, from Kazakhstan, with Boston Marathon bombing suspect Dzhokhar Tsarnaev in Times Square in New York. Kadyrbayev and Tazhayakov, two college buddies of Tsarnaev, were jailed by immigration authorities the day after Tsarnaev's capture. They are not suspects, but are being held for violating their student visas by not regularly attending classes, Kadyrbayev’s lawyer, Robert Stahl said. They are being detained at a county jail in Boston. (AP Photo/VK)

  • Dias Kadyrbayev, Dzhokhar Tsarnaev

    This undated photo found on the VK page of Dias Kadyrbayev shows Kadyrbayev, left, with Boston Marathon bombing suspect Dzhokhar Tsarnaev, at an unknown location. Kadyrbayev and Azamat Tazhayakov, two college buddies of Tsarnaev from Kazakhstan, were jailed by immigration authorities the day after his Tsarnaev's capture. They are not suspects, but are being held for violating their student visas by not regularly attending classes, Kadyrbayev’s lawyer, Robert Stahl said. They are being detained at a county jail in Boston. (AP Photo/VK)

  • FILE - This combination of undated file photos shows Tamerlan Tsarnaev, 26, left, and Dzhokhar Tsarnaev, 19. The CIA added the name of dead Boston Marathon bombing suspect Tamerlan Tsarnaev, to a U.S. government terrorist database 18 months before the deadly explosions, U.S. officials told The Associated Press on Wednesday, April 24, 2013. The CIA's request came about six months after the FBI investigated Tamerlan Tsarnaev, also at the Russian government's request, but the FBI found no ties to terrorism, officials said. (AP Photo/The Lowell Sun & Robin Young, File)

  • Dzhokhar Tsarnaev

    FILE - This wanted poster released by the FBI on Friday, April 19, 2013 shows Dzhokhar Tsarnaev, the suspect the FBI orginally called suspect number 2 in the bombings at the Boston Marathon. (AP Photo/FBI)

  • Katherine Tsarnaeva, Judith Russell

    Katherine Tsarnaeva , widow of Boston Marathon bomber suspect Tamerlan Tsarnaev, leaves the law office of DeLuca and Weizenbaum, with her mother Judith Russell, Tuesday, April 23, 2013, Providence, R.I. The attorneys, Amato DeLuca and Miriam Weizenbaum, issued a statement saying Tsnarnaeva is deeply mourning the bombing victims. They say that Tsarnaeva and her family were in shock when they learned of allegations against her husband and brother-in-law, Dzhokhar Tsarnaev. (AP Photo/Stew Milne)

  • Zubeidat Tsarnaeva

    Zubeidat Tsarnaeva, mother of Tamerlan and Dzhokhar Tsarnaev, the two men accused of setting off bombs near the Boston Marathon finish line on April 15, 2013 in Boston, walks near her home in Makhachkala, Dagestan, southern Russia, Tuesday, April 23, 2013. The Tsarnaev brothers are accused of setting off the two bombs at the Boston Marathon on April 15 that killed three people and wounded more than 260. Tamerlan Tsarnaev, 26, was killed in a gun battle with police. His 19-year-old brother, Dzhokhar Tsarnaev, was later captured alive, but badly wounded. (AP Photo/Ilkham Katsuyev)

  • This Monday, April 15, 2013 photo provided by Bob Leonard shows bombing suspects Tamerlan Tsarnaev, 26, center right in black hat, and his brother, Dzhokhar A. Tsarnaev, 19, center left in white hat, approximately 10-20 minutes before the blasts that struck the Boston Marathon. It's a vexing puzzle about the Boston Marathon bombings: The younger of the two accused brothers hardly seemed headed for a monumental act of violence. How could he team up with his older brother to do this? Nobody knows for sure, but some experts in sibling research say the powerful bonds that can develop between brothers may have played a role. (AP Photo/Bob Leonard)

  • This image taken from surveillance video provided by the Boston Regional Intelligence Center shows Boston Marathon bombing suspect Dzhokhar Tsarnaev at a Bank of America ATM in Watertown, Mass. at 11:18 p.m. on April 18, 2013. The next day, police intercepted Dzhokhar and his 26-year-old brother Tamerlan in a blazing gunbattle that the elder brother dead. Dzhokhar, 19, is charged with carrying out the Boston Marathon bombing April 15 that killed three people and wounded more than 260, and he could get the death penalty. (AP Photo/Boston Regional Intelligence Center)

  • This image taken from surveillance video provided by the Boston Regional Intelligence Center shows Boston Marathon bombing suspect Dzhokhar Tsarnaev at a Bank of America ATM in Watertown, Mass. at 11:18 p.m. on April 18, 2013. The next day, police intercepted Dzhokhar and his 26-year-old brother Tamerlan in a blazing gunbattle that the elder brother dead. Dzhokhar, 19, is charged with carrying out the Boston Marathon bombing April 15 that killed three people and wounded more than 260, and he could get the death penalty. (AP Photo/Boston Regional Intelligence Center)

  • Boston Marathon Explosions

    This photo released Friday, April 19, 2013 by the Federal Bureau of Investigation shows a suspect that officials identified as Dzhokhar Tsarnaev, being sought by police in the Boston Marathon bombings Monday. (AP Photo/Federal Bureau of Investigation)

  • This combination of photos provided on Friday, April 19, 2013 by the Federal Bureau of Investigation, left, and the Boston Regional Intelligence Center, right, shows a suspect that officials have identified as Dzhokhar Tsarnaev, being sought by police in connection with Monday's Boston Marathon bombings. (AP Photo/FBI, BRIC)

  • CNN confirms this was a former Twitter profile picture of the suspected Boston Marathon bomber.

  • Dzhokhar's profile photo on the social networking site vk.com was uploaded on March 19 2012. h/t <a href="http://www.buzzfeed.com/chrisgeidner/what-we-know-about-boston-marathon-bomb-suspect-dzhokhar-tsa" target="_blank">Buzzfeed</a>

  • Boston Police Department <a href="https://twitter.com/Boston_Police/status/325224387731152897" target="_blank">tweeted out this photo</a> of Dzhokhar Tsarnaev on Friday morning.

  • Robin Young (<a href="https://twitter.com/hereandnowrobin" target="_blank">@hereandnowrobin</a>) tweeted a photo of her nephew and Dzhokhar at graduation. She wrote: "My beloved nephew on right, djohar tsarnaev on left, happy cambridge Rindge and Latin grads.heartbreaking."

  • This photo, found on the social networking site vk.com shows Dzhokhar with an unidentified friend. The photo was uploaded 8 April, 2012.

  • Dzhokhar Tsarnaev (shown here, in black, with his face toward the camera) faced Milford High School's Andy Gleeson during a wrestling match in December 2010 in Framingham, Mass.