I was reading about this home invasion/rape/murder today, and one of the comments struck me:
This is one that haunts me. I don't understand how anyone could become so disconnected from their own humanity to have done this.
There's definitely a qualitative difference between a murder committed for money or concrete personal gain, and one committed simply from the desire to harm another person. There are many examples from the last 200 years or so of people who killed others just because they wanted to cause people pain. For the vast majority of us these crimes are unthinkably horrific.
But was it always this way? Do we have evidence of crimes like this committed in premodern history - let's say before the Renaissance, or at least before the Enlightenment? Is it possible that they were even more common before the modern nation state universally imposed the rule of law? How did people see them? How were they punished? Was there always a distinction between murders like those committed by Ted Bundy or John Wayne Gacy, and those committed for money, power, and other personal gain? Are crimes like this known in, say, preliterate hunter-gatherer societies? How do they regard them?
It's a very difficult question to answer.
First, reliable statistics on crime in decentralized societies are difficult to come by. Second, in pre-modern societies, in the absence of a strong state with a monopoly on violence, the exertion of power often rested on the ability to harm those that had wronged you/your family/kin group. Because of this, it is generally understood that murder was a far more common practice in, for instance, the middle ages than it is today.
That being said, there is certainly evidence that serial killers were active before the modern period, particularly amongst those with a high enough status to get away with it. Gilles de Rais and Elizabeth Bathory come to mind.