Wilmington, Del. – A judge has convicted a teenage girl the death of 16-year-old Amy Joyner-Francis, the Delaware student beaten in a girls bathroom at school, while finding a second teen guilty of a lesser crime and a third girl not guilty.

Delaware Family Court Judge Robert Coonin declared Trinity Carr, 17, guilty of criminally negligent homicide and third-degree criminal conspiracy in the death of Amy Inita Joyner-Francis.

Coonin also found 17-year-old Zion Snow guilty of third-degree criminal conspiracy. Another 17-year-old, Chakiera Wright, was found not guilty of criminal conspiracy, according to delawareonline.com.

Carr was the only one who hit Amy during what was called a planned attack on April 21, 2016 at Howard High School of Technology in Wilmington, Delaware, according to a statement from the Department of Justice. All of the girls were 16 at the time. Authorities said in the 20 hours before Amy died, the three  allegedly talked and wrote about what they wanted to do to her.

Cellphone video taken the morning of the fight by one of two other students involved in the fight shows Carr repeatedly striking Amy in the head and torso area with her fist. An autopsy found Joyner-Francis’ fingernails were ripped out during the fight.

Students at the school told WPVI the fight was over a boy.

“They jumped me. They snuck me,” were Amy’s final words, spoken to the math teacher who found her in the bathroom bloodied and disoriented, struggling to get up as her three alleged attackers walked out out of the restroom giggling, according to police testimony.

Defense attorneys claimed Amy died from a rare heart condition after autopsy revealed she had a pre-existing heart defect that led to her death. Officials argued despite the condition, Amy would not have died had the attack not taken place.