I see it just a little differently.
Aaron Hernandez was mentally ill, probably a sociopath. Simply stated, he was a person without a conscience. Sociopaths go through life with little to no empathy for other living beings (human and often, animals). A sociopathic (AKA antisocial) personality disorder (APD) is usually, but not always, the outcome of horrible parenting. There is also evidence that there is a biological component that allows it to develop, because not everyone who experiences the lack of nurturing usually associated with sociopathy ends up as a sociopath.
Hernandez's father died when he was 16. That appears to have been the proximate cause of his mental disorder. He apparently began to act out in the aftermath of his dad's death. As for most of the personality disorders, there is no reliably effective treatment for APD. The aberrant world view that these people internalize is so strongly held and so distorts their perception of reality, that you just can't get "through" to them with counseling (psychotherapy). Drug treatment is also not effective.
Hernandez's suicide also likely reflects that he was severely depressed. It's sad but true that those who are incarcerated usually don't receive the medical and psychiatric care that they need. He was undoubtedly in great emotional pain and decided that this was the only way he could end that pain. I'd like to think that his pain partly reflected some remorse for his actions and for the harm he inflicted on Odin Lloyd and the people who mourned Lloyd's death. To know that he had remorse for his actions would give me some small comfort.
This morning's news is the end of a tragic story. Aaron Hernandez was given amazing athletic gifts—either by nature or by nature's God, according to your religious orientation. Some combination of nature and nurture resulted in him committing murder. What he did was wrong and harmful. Any time I see a human being who, for whatever reasons, ends up falling so short of their potential it is sad. When that person does things that harm others, it is a tragedy.
I feel very sad today for each person who played a role in this tragedy, and Aaron Hernandez was one of those players. If there is a world after this one, I hope that he will find peace there.