unknown neighbor harassing another,Ohio

I live on a small residential street in Cincinnati, Ohio.
Most of the renters and homeowners are caucasion, like myself. Last fall a family bought a home two doors down from my apartment. They began receiving letters from someone in the area complaining about anything and everything they could. The most recent event produced the SPCA at their residence. They have two licensed, well kept, and fairly quiet dogs. The SPCA was told they were unregistered and that they had been in their yard to notice. The unknown harasser has left letter after letter saying that a petition to have them moved out of the neighborhood has been in circulation. I personally have never seen this, but the aggrivation and embarrassment the family has had to endour seems to be getting more extreme. The family is African American and I can't tell if it's racially motivated or not, but they seem to think it is.(They would know better than I) I'd like any advice as to what they can do whether we find the culprit or not. They have small children and that just makes it all the worse.

Until you can find out who might be doing this (and getting a LOT more facts), any answer that we give you is purely speculation.