“...they were mischievous teens.”
Yeah, well now they are dead mischievous teens.
CBP officers are law enforcement officers just like your local police officer or sheriff deputy. And guess what? If you throw rocks and bottles at them, they will probably shoot you, too. I have no problem with the agent’s actions. Nor will I shed a tear for the dead mischievous teen.
I totally agree with you.
You are wrong.
If you were a Police officer, Ernie, and you claimed that you killed a 15 year old with a head shot, on another side of an impassable fence, because he was throwing rocks (when all you had to do was back away from the fence), you will be charged with murder.