In a way, I think someone who looks like this would find it difficult to fit into white society.  I'm sure he suffered from being picked on as a kid - it's what kids do and they can be really cruel.  But then they bully anyone who looks different - whether black, white or brindle. 

It could go some way to explain why he chose to victimise little white girls at a dance class.  Did he feel shunned by kids like this?  Did this build his hatred and resentment?  Or were they just easy targets who couldn't fight back?

Without diminishing his shocking and abhorrent crime, I blame the governments of western nations for bringing in these blacks who are obviously going to have a difficult time trying to fit into the predominantly white society.  The melting pot theory has been found to be thoroughly flawed sociologically and ideologically.  So we now live in a number of parallel societies that don't fit into the prevailing society and all trying to assert themselves. And it's ordinary citizens who pay the price when gangs of these black kids or in this case, one kid with a knife and an absolute hatred of whites chooses to go on the rampage and extract revenge.

One thing we know ... it's going to continue into the foreseeable future.