Where did This Come From

When I say, This, I'm talking about the minority association with crime police officers have. Maybe it comes from back in the Jim Crow Days, when the mid-century policemans philosophy was created.
That philosophy being that any black criminals, suspects or any black showing signs of incooperation was to be scolded physically with violent force, and this approach would keep blacks in place and crime low.

In 1951 William Wesley wrote in his observation of the Indian Police that not one white policeman failed to mock the Negro or use somekind of racial slur. From back in the days the "symbolic assailant" was created. Anyone that uses physical signs, certain verbal gestures, or wearing a certain type of clothing has come to be recognized by police as a prelude to crime.

http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1745-9133.2007.00422.x?cookieSet=1