As far as this shooter, as they almost always are, they may have been programmed by some hate group.
Most "lone wolves" that carry out acts like these have some affiliation with a hate group or militia, yet the proponents of this hate that coerce these troubled individuals are only made culpable in extremely rare cases.
It seems pretty fucked that if you have a cross on your website and claim to be "christian" like a lot of these white power militias and hate groups, then you're somehow not treated like Charles Manson for pushing the buttons of the psychopaths that commit abhorrent crimes like these.
A primary repeat offender is Dr.William H. Pierce (dead since 2002) who wrote the homespun terrorist hate-book,
The Turner Diaries which unfortunately still carries great influence
. Some of his recent followers include bombers Timothy McVeigh and Eric Rudolph, the guys in Texas that dragged the black man behind their pick-up until he was dead, and the guy in L.A. that gunned down eight at a Jewish daycare center. The url for his genocidal National Alliance organization is
www.natall.com. Their symbol is an upside-down peace sign.
If you're appalled at Pierce's thought and his followers (which are growing by the day), please support the Anti-Defamation League.
Their site is
www.adl.org
http://www.adl.org/learn/ext_us/Pierce.asp