Oh, come on now, jft - there are plenty of black vs black murders, just as there are white vs white murders, which are all to do with mental disorders and nothing to do with skin colour. Just occasionally, it really DOES happen - a white person goes berserk and kills another white person because of their paranoia or obsession, a white person kills a non-white, and a non-white kills a white.
They're all mentally unstable, and it's the instability that's to blame, not even the person in a way, since they often don't understand they've committed a crime, or even think that what they've done is wrong. This guy was delusional, as many thousands of people walking around today are. Some of them even think that they've found a way to make money backing horses - now, how crazy is that?
On a slightly more serious note, and not something that gets pointed out too often, there is a slightly higher percentage of black people suffering from schizoid personality disorders than there are white. That doesn't mean that there aren't plenty of mentally unstable whites around, but the schizoid personality is more frequently found in younger black males than in younger white males. Because of the perceived shame attached to mental illness, many families don't want to present the young man for assessment, let alone treatment. It isn't usually until some behaviour gets really outrageous, or the Police are involved, that a psychiatric evaluation is made. In the case of the killing mentioned above, the man had been previously deemed dangerous, but RELEASED - presumably, if there was supposed to be any medical support for him, it failed, as it so often has done in the past when so-called 'cured' patients are once again released into society.
It seems that what failed the family was not so much a deranged male, black or white, but the evaluation system which deemed him fit to roam the streets, and failed to check how his obsessive nature was progressing or worsening.
There are plenty of horror stories concerning obsessives, and their ethnic origin has nothing to do with their behaviour. I was aware of a case, when I worked for Victim Support, where the WHITE male, not content with having killed his little son ('he was taking all of my wife's love away from me'), said he was 'coming back' for the rest out of vengeance. All the family could do was get fitted with a CCTV and better locks and hope for the best - the 'system' said he HAD to be released if the prison psychiatrists deemed him fit to go, even though he was making threats, which he denied he'd made. He WAS released and, because of a banning order not to enter the village where the family lived, he skulked just a mile outside it, letting everyone know he was around, but legally not breaking the order, and so avoiding re-arrest. The Police would have loved to have put him back inside for good, but the fact is, cases are reviewed annually, and if that particular year the person SEEMS to have made progress, out they go!