The whole murder-rate thing is misleading anyway, since, almost overwhelmingly, people who are murdered tend to be killed by a family member or somebody they know. They will therefore overwhemingly be killed by somebody the same colour as they are.

Thing is, murder is a category all of it's own, and really should be separated from other crime statistics. You have murders committed in a blind rage, without thought and planning. You have pre-meditated which can have many different types of motive from revenge to just wanting money. Then you get serial or mass-killers, whose motivations lie in their damaged minds. The professional killer is exceedingly rare, perhaps even a myth.

Economic crimes, however, are more of a piece and the only difference is between the opportunistic criminal, who sees a chance and takes it, and the professional criminal who plans in advance. In either case, the type of crime - theft, fraud, embezzlement, drug dealing or whatever, tends to depend upon the social class or economic status of the criminal, not their skin colour.