Blaming "The Police", or "racism", or any other -ism is why the failure continues and increases. The actual answers as to the causation are pretty simple, but the solutions are far from easy or simple. You can only start at the beginning, and the first order of business must be to restore the nuclear family, which is the very key to any chance at success at all. In terms of morals, values, education, and the passing on and building of wealth (the keys to sucess and happiness in this world) the family is the alpha and omega. If a person does not have a family their success in this life becomes exponentially harder. Tribe or social group is no substitute at all. The nuclear family with one mother and one father is absolutely essential, period. The idea that you can substitute some leftist policy or assistance for an actual family is so absurd you have to be a complete moron to buy into it. It's proof positive that progressives are idiots.
Single parents who raise successful children deserve a medal, because it is a herculean task for which success is fleeting. They literally have to be two places at once, and my heart goes out to them. The ones who do it well are rare, and we see the results of the ones who do it poorly and don't care.
I don't know what the statistic in Ferguson is, but I know that in the City of St. Louis they consider 5% of parents showing up for parent/teacher conferences to be a success. This is a destroyed culture and a destroyed people. They have every right to be angry, but their anger is directed in the opposite direction of where it should be. I wish I could say the church is the answer, but clearly, it's not. Restoring the nuclear family is the only possible place to start, but I don't know how you do that when it isn't even talked about or a consideration, and all of society is focuses on excusing and accepting broken homes as the norm...