IMO JA wanted him dead and he just would not die quickly enough for her. The throat wound cut off his airway and blood circulation to the brain.
Caution: Graphic:
I have looked at the autopsy photos and report. Regarding the throat wound: IMO she slit his throat from right to left. There is a small "hesitation wound" right upper neck where he probably moved. One incised wound. Very sharp knife. Right side deeper than left. She severed major artery and vein (carotid/jugular) on right side, jugular on left. Arteries pump, veins ooze. When you take your pulse in the neck, that is your carotid artery. She transected his trachea, cutting off air supply. Because of the supporting neck muscles being cut, he would not have been able to support his head. Given the fact that he had been stabbed in the chest, with the knife penetrating the superior vena cava and his lung, he was losing blood internally and he only had one lung working. The severed carotid artery pumped blood outside the body at a rapid rate. He had no chance of recovery at this time. While his brain stem was still intact, he continued to try and breathe and his heart was still beating until there was not enough blood to pump.
I think she intended to make him hurt and make him suffer. Which he did. The gun shot was her insurance that there was no chance at life. At all. The bullet entered his skull and started to tumble, most likely tumbling through his frontal lobe, before descending into his left cheek area. The frontal lobe is responsible in part for decision making, processing, motor, verbal etc. If you take a look at the bullet, you can see the flattened portion of where it struck the frontal bone.
Not only did she premeditate this, she wanted him to suffer. For this reason, I think that is why she used the knife first. She wanted him to experience pain. Sadistic. I had initially thought that she shot him first, but after listening to all the testimony, that scenario would not have accomplished what she had in mind. It would have been too quick.
He did manage to try and protect himself as evidenced by the defensive wounds. When you go through muscle, it is exceedingly painful. The stab wounds to his chest would have him on the ground. First instinct is to splint yourself as a result of a chest injury I.e. tuck. Hence the back stab wounds. The human body instinctively reacts to protect itself, both anatomically and physiologically. Blood vessels react by spasming to try to impede blood loss etc. A whole A&P lesson would be involved, so I won't bore you. The body will do everything to protect breathing and maintain the airway. Notice when you hold your breath while swimming. You can't for very long.
JA cut everything vital to survival. She had planned this out no doubt. The horrific injuries she inflicted were purposeful. So I hope this jury reacts with purpose and sentences her to death. Respectfully, IMO
) and its eerily similar angle etc. You grab by the hair tilt the head slightly back and start hacking away. 
