"The only thing I can think of that may help this guy is the medical examiners report stating the teens were mortally wounded and death was eminent before he took the good clean kill shot ."
As I understand it, that wouldn't help in the least. The intent was still to kill the person unlawfully, whether they were mortally wounded or not.
That's like the old law school conundrum.
Guy wants to commit suicide, and jumps off a tall building.
On his way down, his enemy shoots at him, intending to kill him, and in fact does so.
Is the second guy guilty of murder?
As far as I know, the answer is always yes.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.