The choice of research design mostly depends on the present quality of relationship between police and young racial minorities.
If we suppose that before Maya nobody seriously addressed the issue of working with racial minorities in the city, then it would be reasonable to start from establishing trust-based relations between police and youngsters. The best way to initiate this process is conducting ethnography research. Though it can take much time and gaining trust of racial minorities can be really changing task, I believe it is well worth it.
Only this method allows to get high-quality research results concerning social, cultural and economic situation among people belonging to racial minorities. Using ethnography method, it will be possible to get rich quantitative information via composing periodic reports during studies. Besides that, valuable qualitative data regarding actual problems and trends in racial minority communities will be received.
And what is most important, ethnography research results will let Maya’s followers develop optimal strategy of performing further investigations, which will bring the results characterized with a best possible quality. It will be more clear, which people from the community are local leaders and can persuade others to cooperate with the police. And consequently police officers will have people in racial minority societies, on whom they can rely on.
As for techniques of conducting such investigation, I would consider using basic classical ethnographic methods. There are three of them: ethnographic observation, interviewing and results interpretation. All these methods are performed in an iterative manner. All the possible specificity of ethnographic research is covered in a number of studies. As a base, I would use the study “Basic Classical Ethnographic Research Methods” by Tony L. Whitehead.
References
Whitehead, T. (2015). Basic Classical Ethnographic Research Methods. Maryland, MD: University of Maryland.