Aaron Hernandez, the former football player who was serving a life sentence for murder before he died by suicide, had chronic traumatic encephalopathy (CTE), according to a Boston University test.

The neurodegenerative disease has been linked to depression, memory loss and dementia. The Boston University CTE Center test determined Hernandez had Stage 3 CTE, with Stage 4 being the highest.

Hernandez played for the New England Patriots from 2010 to 2012. Earlier this year, he was found dead in his jail cell from an apparent suicide while serving a life sentence for the 2013 murder of Odin Lloyd.

Jose Baez, Hernandez’s attorney, said Thursday at a news conference that he has a filed a lawsuit against the Patriots and the NFL on behalf of Hernandez’s daughter, Avielle. In the suit, Baez alleges that the team and league were “fully aware of the damage that could be inflicted from repetitive impact injuries and failed to disclose, treat, or protect him from the dangers of such damage,” The New York Times reports.

Brian Snyder / Reuters Former New England Patriots football player Aaron Hernandez arrives in the courtroom at Bristol County Superior Court in Fall River, Massachusetts, on April 1, 2015.

In a statement released by Boston University, the researchers who examined Hernandez’s brain released an image and explained what they found.

“This graphic shows the classic features of CTE in the brain of Mr. Hernandez,” the statement reads. “There is severe deposition of tau protein in the frontal lobes of the brain (top row). The bottom row shows microscopic deposition of tau protein in nerve cells around small blood vessels, a unique feature of CTE.”

Boston University The top row shows severe deposition of tau protein in the frontal lobes of Hernandezs brain The bottom shows microscopic deposition of tau protein in nerve cells a unique feature of CTE

A recent study that examined 111 brains of former NFL players found that 110 of them had CTE, according to ESPN. Last year, a top health official with the NFL acknowledged a link between football-related head trauma and the brain disease.

So far, the disease can only be definitively detected through autopsies.

“We are grateful to the family of Aaron Hernandez for donating his brain to the VA-BU-CLF brain bank,” BU said in a statement.

Last year, BMX legend Dave Mirra was found to have had CTE when he died of a self-inflicted gunshot wound.