Well he might be found a murderer or he might be found a manslaughter. To assume either one would be presumptive since they have legal definitions the application of which will be decide in a court of law.
As far as I'm concerned he is a killer and not an "alleged" killer but, for argument's sake, I have given journalists an extreme benefit of doubt. There have been credible reports that some of those hit by bullets may be victims of "friendly fire" which, considering how hellishly chaotic the situation must of have been, is not difficult to believe. I don't believe for a minute that all who died were killed by friendly fire, but...again, benefit of the doubt.
There is, however, every reason to believe he was shooting his gun at people and so he is the Shooter, and not the "alleged" Shooter which some insist upon.
I don't really care whether journalists who wear their politics on their sleeves use "alleged," or not though.
The larger issue is that the PC hand wringing associated with how to portray Hasan in the media is simply one element of a more widespread and dangerous mind set that clearly contribute to the Ft Hood massacre.