BOSTON (CBS) – Aaron Hernandez’s family has filed a federal lawsuit against the NFL and the New England Patriots after tests on the former player brain revealed a “severe case” of brain trauma.

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Attorney Jose Baez announced Thursday afternoon that tests performed on Aaron Hernandez’s brain following his suicide determined he suffered from an advanced case of Chronic Traumatic Encephalopathy (CTE).

The lawsuit has been filed on behalf of Hernandez’s daughter.

Aaron Hernandez. (Photo by Jared Wickerham/Getty Images)

Baez said Boston University researchers said it was “the most severe case they had ever seen for someone of Aaron’s age.”

Hernandez suffered from stage three CTE, a level usually seen in brain trauma patients who are 67 years old. There are four stages of CTE.

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Baez announced the test results at a press conference in Boston. Shayanna Jenkins-Hernandez, Hernandez’s fiancée, was present during the announcement.

Dr. Ann McKee, Professor of Pathology and Neurology at Boston University School of Medicine and Director of BU’s CTE Center and Chief of Neuropathology performed the tests on Hernandez’s brain.

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Test results on Aaron Hernandez’s brain showed severe CTE. (Image Credit: Boston University)

Hernandez was serving a life sentence after being convicted for the 2013 murder of Odin Lloyd.

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In April, he was acquitted in a double murder trial. Five days later the former Patriots star was found dead in his cell at Souza-Baranowski Correctional Center in Shirley.

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Massachusetts State Police investigated Hernandez’s death and ruled it to be a suicide.

When asked if he blames Hernandez’s suicide on CTE, Baez said “We are still investigating everything. But the presumptive answer for that is yes.

Hernandez’s conviction in Lloyd’s murder was vacated following his suicide because he died before all of his appeals had been heard.

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WBZ NewsRadio 1030’s Bernice Corpuz reports