the fact that he was carrying an extra mag was used by the prosecuting counsel as one means of establishing intent.
An allegation easily discredited by having a local LEO testify as to how many spare mags he carries daily with no intent of committing murder
Perhaps. But perhaps not. What the jury takes away from any argument is as variable as the jury itself. But consider these points as rebuttal to using the number of mags an office carries to discredit the original argument (extra mag=intent)
#1) Number of mags is the officer's duty equipment, he doesn't pick it.
#2) Officers are required by their jobs to go in harms way.
#3) Knowing they are going to be in harm's way, depts. make them carry spare mags. The officers intend to go in harms way, as part of their duty to protect us. etc., etc.
"The defendant chose to carry extra ammo, showing his understanding that it might be needed, because he intended to go in harm's way. Unlike an officer, he was not obligated by his job, or an oath, he chose to do it, on his own. He intended to go into a high risk situation, and he did, when he didn't have to. He sought the confrontation. This case is a result of that."
One can phrase it a lot of different ways, but the argument can be made, and once made, the jury will consider it.
(the example I just gave would not apply to a lot of defensive shootings, but does, to a degree in that one case.)
We carry a spare mag, speedloader or even a back up gun, intending to go about our normal daily lives and business. Not seeking trouble, but prepared so that if trouble finds us, we have a chance of going home alive.
This case was (as I understand it) not that.