This was on recently, and wow. For a 50 year old movie it was pretty graphic and hard hitting. It sure got a lot past the censors of the day. Even by today';s standards this movie is a very hard edged film with some hard to watch scenes, especially when you realize it was all reality based.
The major thing about the movie is that while filmed in monochrome is was very much not a black and white movie, unlike a lot of movies filmed in full color. The characters were all portrayed in very full, very graphic and very human fashion. The victims, the murderers, the police and the court personnel were all human, warts and all. We had to see the murderers as human beings who were once chldren with parents. The movie was also pretty frank about sex, almost unheard of in its day.
In cold blood isn't a fun movie, it's not easy to watch and can make you very uncomfortable, all of which make it a real masterpiece.
I love this movie. Watched it again a few months ago (and then watched the Anthony Edwards/Eric Roberts remake a few days later). I read the book somewhere around 1991 - 92 and it's one of my all-time favorites.