Since everyone seems to be answering for everyone else I will put in my two bob`s worth. If he did see her, then it is definitely murder eh. If he didn`t see her he still managed to hit her with three out of four bullets which, had she been an intruder and standing in the same position the end result would have essentially been the same. For all his talk of not meaning to shoot anyone, he was fully aware of what his gun was loaded with and the capabilities of that type of ammo.
Remember that the state's version is that she was arguing with him which is why she was standing facing the door but she was also on their version screaming in terror for around 5 minutes because she believed she was about to be attacked.
The question is, did he think he had the right to shoot when he perceived that there was an 'intruder' there?