Updated

The trial of three girls charged in a fatal school bathroom fight in Delaware began Monday with a prosecutor playing a cellphone video of the altercation.

A 17-year-old girl is charged with criminally negligent homicide, and the two other girls are charged with conspiracy. All three are being tried as juveniles.

A defense attorney told the judge before opening statements that the case raises serious questions about the standard to which a teenager with a developing brain should be held in determining whether she acted negligently. He also said no one could have foreseen that the fight last April at Wilmington's Howard High School of Technology would lead to the death of 16-year-old Amy Joyner-Francis.

An autopsy found that Joyner-Francis, who had a heart condition, died of sudden cardiac death.