I personally believe the black crime thing is not specifically a race issues, it is merely coincidence. To expand on that, you have to look back into history for hundreds of years.
The matter of fact here is that dating back to the times of the earliest civilized societies, Africa was not one of them. In terms of pure societal and civil progress/advancement, Africa along with much of the Middle East has always been many decades and in some cases a century or more behind what at the time was considered the most advanced societies, mainly based in Europe. An advanced society can of course be defined subjectively based on technological advancement, advancements in the structure and role of the government (or even the existence of a government in the first place), organized labor, criminal regular via a system of laws, etc.
And this advancement and progress of society for any geographical region is obviously affected by other nearby regions. No doubt many societies in Africa and the middle east were held back by common factors such as war, religion, geographical bias towards (or away from) survivability in the sense of how the land can aid in survival of a society (more on this later), and influence or control from neighboring societies among others. The simple truth of the matter is, many societies in Africa and the middle east were very much inhibited by the land they occupied, and as a result, their progress in the field of societal advancement was slowed.
Is it any coincidence that the most civilized societies throughout history lived in areas that had good natural resources, good land for farming, good access to a more complete food chain (animals, fish) and good areas in which to build on?
I personally believe if you put any society into Africa back in the day it was originally populated, that same "race" would be in the same place African americans are now. The progress of the race was held back by many factors, many centuries ago, and has slowed their advancement since. The high crime rate by blacks nowadays is merely a long-last side effect of all this. If you want to look at the British that came to North America to settle it, direct corrolations can be made in the typical society behavior of those people compared to african americans 50-70 years later.
All humans are bred with certain animalistic tendancies which are weeded out, very slowly, over time. The simple fact is that the current group of african americans were held back by geographical and societal factors many centuries ago, and they are simply "catching up" in terms of advancement of their race. This is why there is noticable progress. The same can be said of many societies in the middle east that exhibit a lot of the same tendancies towards violence.
If you swapped the white people that were in Europe 700 years ago with the black people in Africa 700 years ago, it would be the whites that were brought to America as slaves, and the whites who committed 7 times more murder per capita today. It is merely coincidence that it is the blacks, and it is only an issue of time before enough progress in the advancement of the race occurs to weed out the tendancies that lead to this type of behavior. Yes, social programs, aid for the poor, etc. can help this along, but ultimately it is just a matter of time.
In the long run, after many decades and centuries more of advancement on the part of all societies, behavior that leads to murder and crime will be nearly bred completely out of all races, and argument like this will be completely moot.
So, I blame the actual continent of Africa, it's climate, it's geography, it's lack of abundant farmland and natural resources (compared to areas such as America, Europe and the far east) as well as the influence of unruly neighbors who just happen to be more technologically advanced and used that to take advantage of the people they could.
There is no gene in blacks that isn't in every other human being, it just hasn't been surpressed to the same extent as it has with whites, for example.