The only detail I remember is that of a tall, thin black guy with a mustache coming up behind another black guy who was bent over a drinking fountain under the eaves of a house, throwing some kind of garrote around his neck, strangling him immediately, then grabbing him by the head and throwing him straight up, crashing through the overhanging eaves and landing on the roof.  He then turned to me and told me, in effect, that the same thing would happen to me if I reported the incident.  I pretended to be intimidated, but secretly was making careful mental notes of his description so that I could inform the police when I thought it was safe to do so.  The dream had an intricate plot which I don't remember, and involved a lot of this sort of violence.