If one murder is remembered and another not, it's often for strange reasons that aren't too irrational. Lots of people died in Victorian London but Jack the Ripper's crimes are remembered above them all -- even Mary Ann Cotton is far less well-known. In the modern case Stephen Lawrence's murder is remembered primarily because his mother kept the case in the public eye -- and that, because she could not get justice in her eyes.
It's not comparing like with like. We have a case here where the criminals were charged and found guilty within about a year of the crime, and prosecuted far earlier than that. While the crime is sad, horrible and brutal, justice has also been seen to be done. That never was the case for Stephen Lawrence.
I wonder, too, if Madeleine McCann will be the only missing child case remembered from the last decade. Very possibly. That's because her parents kept the case in the public eye, and not for any more sinister reasons.
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Video games only ever act as a catalyst for violent people. I'm sure that they make an impression on those who would be violent and nasty and horrible and brutal. But you have to be "lost" already for it to make a real difference. If you can o longer distinguish between reality and fiction. And if that happened already, then the nastiest fiction will leak into reality. But if you have the barrier there, if you've been brought up to distinguish the two, then no amount of brutal massacring of pixels is gong to make you want to go out on the streets and do the same.
If people watch video games and then go out and be violent, they had already lost perspective.