Not sure where you get this murder idea from, the news articles I found on this case said foul play is not suspected. And if it's connected to the cases of the feet found washed ashore (which it presumably is), those are not suspected to be the results of murder either. Not to get too graphic here, but when a body is submerged for a long period of time decomposition will begin, and the bones will break apart, however when the person is wearing a running shoe (which I believe all of the feet cases were, as well as the case today) that traps the remains in the shoe. And that's how you end up with all these feet washing ashore; the person likely drowned, they weren't actually murdered.
In regards to someone who would actually decapitate someone, I sincerely doubt it's becoming more common. There's always been psychos out there, and there always will be. When you actually think about how many serial killers or mass murders there's been in the last 50 years, it's a tiny, tiny percentage of the population. Barely even significant if it weren't murder we're talking about. The biggest thing that causes this illusion of things being worse, when they're in fact safer than ever before, is the access to information we have. We've never had this much access before, so of course we're going to find out about every single pedophile, murderer, and rapist in the entire world. 100 years ago, you knew what was happening in your own town only. The second contributing factor is that over last several decades, the need to sensationalize has grown steadily. So the media makes a mountain out of a molehill essentially, all to just to get an audience and make money. Things are safer now then they've been in the history of humankind, so let's not jump to hysterics.
