I don't know exactly how you need to use Blackwell, but maybe you need something more drastic then "bribes" to make him threatening? Or if you like the bribe angle, have a snippet about him getting violent when it was reported? It just feels like it should be something scarier then, "Dudes slipped him a few twenties!"

Couple of ideas:
War Crimes? (That's drastic tho, dunno if you want to go that scary)
Racist and kicked out for it?
Merciless/enjoyed killing?