In April 2017, former New England Patriots player Aaron Hernandez killed himself at age 27 in jail two years after he was convicted of first-degree murder, and sentenced to life in prison without parole. Now, in an upcoming two-part TV documentary for Oxygen called Aaron Hernandez Uncovered, the late NFL star’s fiancée, Shayanna Jenkins-Hernandez, is speaking out about his tragic last days.

In a sneak peek, Shayanna, 28, opens up about the joy of welcoming her now-five-year-old daughter, Avielle Janelle, with the athlete. "In November [2012], I had given birth to our daughter," the mom-of-one says. "She was born on his birthday."

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Shayanna with daughter Avielle.

Elsewhere in the clip, experts talk about Aaron’s involvement in a subsequent murder trial, this time for a double homicide that occurred in 2012. Shayanna recalls her emotional response when she found out that the father of her only child was acquitted of the crime. "When I heard not guilty, I cried," she admits though tears.

Despite his legal victory, Aaron took his own life just days later. The state medical examiner ruled the death as asphyxia by hanging. Researchers who examined Aaron’s brain after his death determined he had a severe form of chronic traumatic encephalopathy, more commonly known as CTE.

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According to a September 2017 report from the New York Times, Aaron’s attorney Jose Baez said during a press conference that researchers described his CTE — a degenerative brain disease linked to the repeated head trauma found in more than 100 former NFL players — as "the most severe case they had ever seen in someone of Aaron’s age."

Shayanna previously filed a lawsuit in Massachusetts federal court against the Patriots and the NFL on behalf of the couple’s daughter. The suit claims the Patriots and the NFL 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," via TMZ.

Part one of Aaron Hernandez Uncovered airs on Oxygen Saturday, March 17, at 7 p.m. EST.