A 17-year-old Delaware girl has been convicted of homicide nearly a year after she was involved in a school bathroom fight that left another teenage girl dead.

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Delawareonline reported that autopsy reports showed that Amy Joyner-Francis, 16, died of sudden cardiac death brought on by physical and emotional stress from the April 2016 brawl in a Howard High School of Technology bathroom. The incident was caught on cellphone video, and the assailant was found guilty of criminally negligent homicide for her participation in the fight. Two other teens were charged with misdemeanor conspiracy.

Related: 3 teens charged in death of high school student

According to court documents obtained by Delawareonline, defense attorneys argued that Joyner-Francis' death was unpredictable because her rare heart condition, Eisenmenger syndrome, had gone undetected by doctors, and there was no way of knowing that death was a risk. They also said the girl willingly engaged in the fight against "mutual combatants." Prosecutors, however, maintained that Joyner-Francis did not want to participate in the altercation and would not have died had the other girls abstained from violence.

"Distress, the unexpected nature of the attack, the brute ferocity of it raining upon her, all led to Amy's death," deputy attorney general Sean Lugg said in closing arguments. He said the assailant displayed "a level of barbarism that reasonably would result in the outcome."

Prosecutors said the fight stemmed from an online group chat about a boy. A Snapchat video shared by one of the defendants showed Joyner-Francis attempting to defuse the situation in the bathroom, with a caption explaining that the teen convicted of homicide was “bouta fight her.”

A judge ruled last year that the assailant would be charged as a juvenile, sparing her the possibility of going to prison for up to eight years. Because she was tried as a delinquent, she is subject to supervision until she turns 19.