(CNN) On October 10, 2012, shortly before midnight, 16-year-old José Antonio Elena Rodríguez took a walk.

It was a peaceful walk along the Calle Internacional, which runs parallel to the US-Mexico border. Then, without warning, the bullets came.

And they kept coming, between 14 and 30 of them, all from the Nogales, Arizona, side of the border. About 10 of those bullets hit José, most of them in the back, and killed him.

They came from US Border Patrol Agent Lonnie Swartz, who aimed his pistol at the teen through the border fence.

The teen's mother, Araceli Rodríguez, sued Swartz for violating her son's constitutional rights. When the agent appealed on the grounds of qualified immunity, the courts were left to decide if the suit should stand.