The movie "Mississippi Burning" is in one way or another based on real events. The plot in the movie is about the murder of three men in a small local town of Mississippi. Therefor Agent Rupert and agent Alan are sent to investigate the events in the little town. Rupert and Alan ere very different men and therefor have very different ways of investigating the murders. If you want you could say that somehow they are running the classical "Good cop and bad cop" technic.
When you first see agent Rupert Anderson you can't really be sure if he is taking a Parton the problem or not. He sings songs related to the KKK and just in the overall movie he seems some kind of happy considering the brutality of the crime that he is currently investigating in Mississippi. We find later that he does it all sarcastically. Agent Anderson is from the southern states himself so he know how to talk the local language. He also know how to dress like the local people. He has no jacket and keeping the hat on. Despite the very smiley and happy appearance agent Anderson has he is a really tough fellow. He is not afraid to use violence to find his way through the masses if he has to. Agent Alan ward is in some ways the good cop. Unlike agent Anderson he is the fresh new agent that does everything by the book. Agent Ward stands very much out from the crowd in the little town. He looks very much like a young man from upstate. Agent Anderson is worried about the case because agent Ward always does everything by the book. Anderson is sure that by working like Alan ward will only cause problems in the investigation. There is an exact place in the movie where I think personally that the difference of the two characters are described very well: Agent Ward: You wanna drive, Rupert?
Agent Anderson: Yeah.
Ward: Just don't lose sight of whose rights are being violated! Anderson: Don't put me on your perch, Mr. Ward.
Ward: Don't drag me into your gutter, Mr. Anderson!...