This is the nature of America's racist fascist state of mind. The black-as-criminal image has been with us at least since the nineteenth century, when explicit racism portrayed African American slaves’ essential nature as ignorant and savage, in need of the “civilizing” influence of the white man.  At that time little black crime actually occurred, as slaves’ lives were rigorously controlled, and they could be and often were swiftly put to death for perceived offenses against the slave owners, who acted as judge, jury, and executioner.  As Chief Justice Roger B. Taney said in the famous 1857 Dred Scott v. Sanford decision about the Founding Fathers’ mindset in drafting the Constitution:

Blacks had no rights which the white man was bound to respect; and that the negro might justly and lawfully be reduced to slavery for his benefit. He was bought and sold and treated as an ordinary article of merchandise and traffic, whenever profit could be made by it.