Garsh said there may be "complex and myriad" reasons that Hernandez killed himself five days after he was acquitted in a 2012 double murder. He was convicted this year in the June 2013 killing of Odin Lloyd.
Citing a suicide note in which Hernandez told his fiance "you're rich", district attorney Thomas Quinn said the National Football League star may have killed himself to protect his family assets.
But Garsh said that she was compelled to follow precedent and threw out the conviction.
The prosecutor added Hernandez forfeited his right to appeal by taking his own life and that more courts in the country where moving away from allowing abatements.
Quinn argued, "despite the tragic ending to Aaron Hernandez's life, he should not reap the legal benefits of an antiquated rule".
As Crime Online previously reported, the prison file included notes from interviews with Hernandez's fellow inmates following his suicide.
Ward said she would always see Hernandez as guilty despite the technicality, but that she wasn't angry because "God didn't raise me like that".
But, as CNN reports, prosecutors argued that the abatement should not apply in this instance because of what they said was evidence that Hernandez had taken his own life with the intention of getting this very result.
On April 15, 2015, Hernandez was found guilty of first-degree murder after the 2013 killing of Lloyd, a semi-professional football player who was dating Hernandez's fiance's sister.
Ursula Lloyd, Lloyd's mother said despite the judge's ruling, it won't change how she views Hernandez.
Hernandez's appellate attorney told the judge that the state's highest court has applied the legal doctrine "without exception", even in cases of suicide.
Hernandez's attorneys praised the judge's decision and declined to answer reporters' questions on whether it would have any influence on civil lawsuits by the families of the men he was accused of murdering.
Hernandez attorney John Thompson said the manner of death should not matter - when a person dies while his conviction is under direct appeal, the conviction should be vacated.
Susan Garsh erased the late Aaron Hernandez's murder conviction. One of the documents was the suicide note Hernandez left to his fiancee, Shayanna Jenkins-Hernandez.
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