Just like all of the other mass shooters.
This is why they are pushing the mental health issue so hard. If he had been a conservative they would be stressing his political affiliation.
Truth be told a weak mind is symptomatic of Obama supporters so I guess they aren't really hiding anything.
Mass shooters are:
Democrats or children of democrats (if too young to register)
On psychoactive drugs - usually antidepressants.
NONE of them have been members of the NRA. None of them have been Republicans. None of them have attended Church on a regular basis.