According to the Milwaukee Journal-Sentinel, he was a neo-nazi.

The Southern Law Poverty Center, a group that has studied hate crimes for decades, reported Monday that Page was a frustrated neo-Nazi who had been the leader of a racist white-power band known as End Apathy.

 

He bought the gun within the last ten days. NBC News observes:

Wisconsin has some of the most permissive gun laws in the country and had passed a law in 2011 allowing citizens to carry a concealed weapon.

‘Nuff said.