WILMINGTON, Del. --A Delaware judge on Thursday convicted a 17-year-old girl charged with homicide after a school bathroom fight that left a 16-year-old girl dead.
Family Court Judge Robert Coonin delivered his ruling after hearing a week of testimony in the nonjury trial.
An autopsy found that Amy Joyner-Francis died of sudden cardiac death, aggravated by physical and emotional stress from the April 2016 fight at Howard High School of Technology in Wilmington.
Her assailant was charged with - and ultimately convicted of - criminally negligent homicide for her role in the fight, which was captured on cellphone video.
Two other 17-year-olds were charged with misdemeanor conspiracy. All three, who were 16 when the fight happened, were tried as juveniles.
Defense attorneys argued that the death of Joyner-Francis, who had a rare heart condition undetected by her doctors, was unforeseeable. They also suggested that she was a willing participant in a fight between "mutual combatants."
Prosecutors argued Joyner-Francis was not looking for a fight but trying to avoid one, and that she would not have died had she not been assaulted.
"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 during closing arguments this week, adding that the alleged assailant showed "a level of barbarism that reasonably would result in the outcome."
Attorney John Deckers, representing the girl charged with homicide, argued that she shouldn't be held culpable for Joyner-Francis' death because a reasonable person would expect the consequence of a school fight "is not death, but rather discipline."
All three girls charged in the case opted not to testify.
The Associated Press is not naming them because they are minors.
Coonin ruled last year that the girl charged with homicide would be tried as a juvenile. Had she been tried and convicted as an adult, the girl would have faced up to eight years in prison. Being declared delinquent, she would be subject to supervision until age 19.
Dr. Richard Ringel, a pediatric cardiologist and professor at Johns Hopkins University, testified that Joyner-Francis suffered from Eisenmenger syndrome, an extremely rare condition for someone her age in which a heart defect combines with severe pulmonary hypertension.
While Ringel did not dispute the autopsy results, he said there was no way of knowing that Joyner-Francis was at risk of sudden death, any more than a person could predict that an athlete who appears healthy and fit one day suddenly collapses and dies on the playing field the next day.
Prosecutors said that in an online group chat the day before the attack, Joyner-Francis offered advice to one of her friends about a problem involving a boy, telling her friend to "just be careful." A detective testified that the defendants were later brought into the chat, and that the alleged attacker thought Joyner-Francis - who had warned that someone might betray another person - was talking about her.
A Snapchat posting by one of the defendants that same day shows Joyner-Francis talking to her alleged assailant in the bathroom, purportedly to try to defuse the situation. The posting notes that the girl later charged with homicide was "bouta fight her," followed by several emojis indicating that a person was laughing so hard she was crying.