Dallas Cowboys player Marshawn Kneeland who died by suicide diagnosed with CTE brain disease BBCNFL star Kneeland posthumously diagnosed with CTE RTE.ieFormer Cowboys defensive end Marshawn Kneeland had early stage CTE when he died at 24 The GuardianMarshawn Kneeland’s Cause of Death Revealed, Dallas Cowboys Player Was 24 People.comLate Cowboys player Marshawn Kneeland diagnosed with CTE ESPN