The defense can put forth any theory they wish, but if the gunshot to the head was the final wound, the defense will look like fools if they insist it was the first.
The ME's report will provide a wealth of information.
The State has repeatedly said the gunshot to the head was the last gunshot wound. I don't believe they would make this claim if they couldn't back it up with medical evidence.
I wonder if they will rely on the same report or have separate experts with conflicting assessments. I think the defense has similarly claimed their theory.