I think the pagans will be highly embarrassed when they have made a huge stink about the evil Christains and then find out the this was merely some practioners of Santeria exercising their rights to freedom of religion!
One of the reasons i've bristled at the presumption that this *had* to be a Christian was that it just didn't seem like the sort of thing a Christian wack job would do. The offense itself seems just too pagan. And by pagan, I did not specifically mean wiccan. It's just seems against the Christian concept of "dirty." And when I say "dirty," I don't mean "vicious," or "sneaky" or "unfair." I mean unclean.
But one thing I have learned is that unbalanced zealots usually strike at what is uncomfortably close. A person who considers himself Christian, but has had a real bad experience with Wicca, and maybe even faces a very strong temptation for its power, might actually fit this. Whereas a more distant Christian, like myself, might see it echoing Wicca, he or she might have chosen that style specifically because it might be more hurtful.
At first I discounted the "desecration" motivation because it seemed like the offense didn't mimic any wiccan practice that I know of closely enough; stealing the head sounds more mass-murderer than animal sacrifice. But what if it's not meant to be a mockery of paganism (in the way a black mass is a mockery of a mass) (and keep in mind, I mean mockery in a very ancient sense here), but rather it's supposed to be an assault on the logic of paganism.
Think about the way Satan has moved against the Church: not so much by the conduct of black masses. These may be going on, and they may be a tool for desensitizing people, but if they are going on, Satan has tried to keep their presence quiet. No, what has been such the destructive blow to Christianity are strikes against the logic of Christianity: It is practiced as a social function to preserve the faith for future generations. Christianity is counter-cultural in that it teaches sacrficie for children, sexual modesty, and purity. So how does Satan attack Christianity? By sexually defiling children! How would one attack a wiccan?