She must have fitted the profile of some dodgey goings on.
I have been questioned by police plenty of times when I was in my younger years when I was simply hanging around. I didn't go blaming racism though. But if the black community in that area has a high crime rate, then it is human nature that you would be weary of other blacks in that area.
The same way you would be weary of white lads late at night who wear Adidas shorts, striped Nautica shirts and Nike sneakers.
