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KANSAS CITY, MO — The body of former NFL linebacker Jovan Belcher was exhumed Friday in order to perform tests on his brain, a lawyer for the player’s family told the Kansas City Star.

Attorney Dirk Vandever told the newspaper that Belcher’s family hopes tests will provide a clue as to why the four-year veteran of the Kansas City Chiefs shot his longtime girlfriend to death then killed himself about a year ago.

Belcher’s body was exhumed Friday from a cemetery in Long Island, New York, the paper reported. It was not clear where the body was sent for examination.

Vandever didn’t immediately respond to CNN’s calls for comment Sunday morning.

The family wants to know if chronic traumatic encephalopathy, known as CTE, or something else played a role in the murder-suicide, according to the newspaper.

CTE is a progressive degenerative brain disease found in some athletes with a history of repetitive brain trauma.

The only way to diagnose CTE is after death — by analyzing brain tissue and finding microscopic clumps of an abnormal protein called tau. Tau has been found in the brains of dozens of former NFL players, including Junior Seau, Dave Duerson, Terry Long and Shane Dronett, who all committed suicide. It was also found in the brain of Mike Webster, who died in 2002.

Dr. Bennet Omalu, the first forensic pathologist to diagnose CTE in NFL players, told CNN time is a factor in the Belcher case.

“There is a reasonable probability that the (brain) tissues would have degenerated, but until you open the body up, you may not know if there would be viable tissue for reasonable analysis,” he wrote in an e-mail to CNN on Sunday.

Omalu said there was a 50-50 chance that the study of the brain would yield results after the body had been buried about a year. He said he had performed two such studies himself.

“The exhumation and analysis has to be performed by a forensic pathologist who has the experience and expertise, otherwise it has the potential of coming to naught,” he said.

Scientists are working to identify some common symptoms of the brain disease in living players. Experts say athletes with CTE often struggle with memory and decision-making. Some exhibit mood and behavior problems such as depression and hopelessness, or violent, explosive behavior. A few show no symptoms at all.

In 2002, Webster, a Hall of Fame center for the Pittsburgh Steelers, was the first former NFL player to be diagnosed with CTE. After his retirement, Webster suffered from amnesia, dementia, depression and bone and muscle pain.

Other athletes have demonstrated erratic behavior, such as Pittsburgh Steelers offensive lineman Justin Strzelczyk, 36, who died in a 2004 high-speed chase. Cincinnati Bengals wide receiver Chris Henry died at age 26 after falling from the bed of a moving pickup during a fight with his fiancee.

Issues surrounding brain damage, and other potential long-term cognitive and emotional consequences of repetitive brain trauma, have become a serious concern for the NFL.

The league settled a concussion lawsuit for $765 million in August. At the heart of the lawsuit were plaintiffs’ allegations that the NFL led a deliberate misinformation campaign — primarily through its Mild Traumatic Brain Injury Committee — to deny scientific data being presented in the medical community about concussion risks.

The deal calls for the NFL to pay for medical exams, concussion-related compensation, medical research for retired NFL players and their families, and litigation expenses, according to a court document filed in U.S. District Court in Philadelphia.

The agreement involved more than 4,500 plaintiffs.

Belcher — who was 6-foot-2 and weighed 228 pounds — played for the Chiefs from 2009 to 2012, appearing in 59 games. On December 1, 2012, the 25-year-old linebacker fatally shot his girlfriend, Kassandra Perkins, in the same home with their 3-month-old daughter before heading to the team’s practice facility, thanking his coaches, and turning his gun on himself.

In an November article on Bleacher Report, a friend of Belcher’s said the linebacker played through his physical problems.

“Jovan suffered multiple concussions,” said Kash Kiefer, a former punter at Maine and one of Belcher’s closest friends. “But in football, you don’t complain. You play. That was Jovan. He played.”

Belcher was from West Babylon, New York. He played for the University of Maine Black Bears, where he started in all 45 games of his four-year career.

By Steve Almasy

CNN’s Stephanie Smith contributed to this report.