Nightly News | December 15, 2013
>>> a major new development involving a star nfl player who shot and killed his girlfriend and then himself last year. the body of kansas city chiefs linebacker jovan belcher's body has been exhumed. they hope it will determine whether a brain injury was a factor.
>> reporter: more than a year after the murder-suicide, his family still wants to know why. ordering the linebacker's body exhumed so his brain can be examined for chronic traumatic encephalopathy. he killed his girlfriend, the mother of his 3-month-old daughter.
>> okay. they were arguing and he shot her?
>> yes. yes. they were arguing.
>> reporter: then in the parking lot of the chiefs' practical facility, shot himself . at the time his family mourned the man they knew.
>> his kindness, humility, respect and gratitude for family and friends were steadfast.
>> reporter: now they wonder if his years on the field could have damaged his brain.
>> he had a lot of hits as a linebacker. probably including a lot of concussions that went undiagnosed or unreported.
>> reporter: doctors at boston university recently reported finding cte in the brains of 52 of the 54 deceased nfl players they tested.
>> we know in many cases how this manifests itself. suicide, dementia, severe memory loss.
>> reporter: last year retired nfl great junior seo committed suicide . his brain pathology confirm cte . in 2011 , the bears safety shot himself in the chest leaving a note donating his brain to the nfl brain bank. it too showed cte . experts say a similar diagnosis for belcher may not explain everything.
>> even if jovon belcher is bound to have cte , that doesn't mean it was the cause of the murder-suicide.
>> reporter: but his family hopes it is a step toward understanding what led to the unthinkable. nbc news, new york.