The lead plaintiff in the NFL's concussion lawsuit had CTE.

FOX's Chris Hoenig reports: 

Kevin Turner was chief among the 4500 former players who sued the NFL, accusing the league of hiding concussion risks that led to dementia, depression and suicide.

In 2010, Turner was diagnosed with ALS after experiencing weakness in his hands and arms. He died in March, just 46-years-old.

But Boston University School of Medicine lead researcher Dr. Ann McKee says Turner not only had the brain disease Chronic Traumatic Encephelopathy, but it's stage 4 severity was extraordinary and unprecedented for an athlete who died in his 40's:

(Dr. McKee) "Years of playing football can result in debilitating, devastating disease and death by the age of 46."

The NFL agreed to a $1-billion settlement in the lawsuit, covering more than 20,000 retired players for the next 65 years. Turner's estate will receive $5-million from that.

Chris Hoenig, FOX News.

Follow Chris Hoenig on Twitter: @Chris_Hoenig