Given the story, the final judgement would be suicide. Considering husband and wife were not aware of the load gun, the son was, and his suicide was not going to be possible. The shooting results in his unintentional assisted suicide, and failure to keep gun secured. Case closed.
Ehh, I hate it when someone makes a good story and it ends up being fake because then you have many people who believe it and sound like idiots when they are being proved wrong.