Not that I want to help serial killers, but...

Statistically the best victims are black because their murders have the lowest solve rates(59% black vs 87% for whites). Chicago is even worse with 21.7% solve percentage in black neighborhoods compared to 45.6% in white neighborhoods.

So targeting black people in black neighborhoods in Chicago gives you better odds, which can be further increased if you target homeless people or sex workers and kill through means that can be dismissed as accidental like overdose.