Bernard Campos and David Serbeck are both ordinary, reasonable middle-aged family men living in Utah. Both parents of multiple children, one a CPA, the other a former army sniper. Neither have any mental illness or are known to have committed any crimes. However, due to bad timing and a couple of guns, one is paralyzed and the other on trial.
Serbek's neighborhood had been targeted by a spate of minor crimes -- mailbox thefts. There was a description of the vehicle, so he and a friend, the president of the homeowners association, decided to cruise around looking for the car. While looking, they stopped quickly to avoid hitting two girls and claim that they said to them "Be safe going home." A few minutes later they saw a car they thought matched the description and followed it, giving up when the car sped onto a main street. It was almost midnight.
A bit earlier, Campos had received a call from his daughter, who told him that a man had almost accidentally hit him in a car and that she was disturbed by the exchange. She had gone to get her car and retrieve a couple of friends from a party, and also claimed that Serbecks car had been following her for a while.
Fast forward to Campos finding Serbeck still looking for the mailbox thieves. What transpired isn't completely clear, but the two exchanged a few sentences. Both carried guns and Serbek wound up on the wrong side of the exchange. More details on this story can be found here.
At it's face, this case appears to be a textbook example for gun control rights. Two reasonably normal people, motivated by all the right reasons in a confusing and emotionally charged situation. In the heat of the moment they reached for the convenience of their nearby weapon and one innocent man will never walk and the other may go to prison (and regardless will spend the rest of his life knowing he shot an innocent man).
No lives were in danger, no one had called the police for help.