I don't know what it's called when in crime related tv or movies the connections between all the people of interest are illustrated by putting their pictures on

I don't know what it's called when in crime related tv or movies the connections between all the people of interest are illustrated by putting their pictures on a board and linking them with bits of ribbon ? Whatever it's called this story would really benefit from one of those. I've read it twice and I really wouldn't want to provide a verbal summary.