The idea that people are fascinated with crime and suffering is not a new concept. For millennia human bloodlust has been sated in the form of gladatioral combat, public executions, and amongst other things the all too common violent crime. So the main question I guess is why the fascination with violence?.
The human condition is one of constant struggle with external as well as internal conflicts. Form the day we learn to walk we experience one of life's fundamental realities. Pain. A child takes his first joyful steps just to surcome to gravity and return to a life on all fours. In the teenage years it is common for an individual to experience all the savage realities of life as a sub-adult, while missing out on the respect that comes with maturity as well as the leniency that comes with adolescence. So we learn to value the moments where we are healthy and content and allow ourselves to relate in some respects to those who are less fortunate. .
But I think the human fascination with violence goes far beyond anything we can observe or even comprehend. We were born of the jungle; at first small, fruit eating simians who feared everything but the meekest amongst our own ranks. But as we evolved so did the brain and that required more protein. It is thought by some scientists that the requirement for more nutrient rich foods gave rise to our species becoming carnivores. So now we are a large, hairy, savage creatures who consume raw meat and are excited by the sight of blood and the thrill of the hunt. Not to mention that somewhere along these lines one of them, one of us, woke one day and went to the river to drink, only to realize that the reflection staring back at him was his own.