Byron Smith was convicted by the evidence he himself had gathered with his recording equipment. This recording established a timeline for each shot he fired and proved that he not only ambushed those kids but he then executed them as they lay wounded in his home. But not for the recorded evidence, he could have sworn that they came down the stairs together, they pointed an object at him he thought was a gun, he feared for his life, he fired until he ran out of bullets, and he could have stuck to that story with no one alive to contradict it.
Mr. Smith committed several crimes here and he was stupid enough to record himself doing it, so in my humble opinion he fully deserves the sentence he received.
But he made the prosecution's job supremely easy.