This post shows that blacks kill LEOs at more than triple their population level, while being killed by LEOs at only twice their population level.
From the link quoted there, whites make up 52% of those killing LEOs. They are under-represented per capita, as the white population makes up 63%. However, whites killed 44% of the LEOs . Hence, LEOs kill whites (52/44) 20% higher (1.19) than the proportion of their threat, while killing blacks 0.7 (33% lower) than their threat level. Thus, if cops are racist, it is against whites, killing them at a higher rate than their threat level would indicate.