In my current project, Molly, I use mainly primary sources and secondary sources such as news articles, as well as well-vetted research in order to build the story around the cold case.
The drawings are then freely inspired from the research, i.e. they are an artistic interpretation.
I can combine my research to build portraits.
I am trying to stick to the facts in the text, avoid assumptions, yet draw conclusions.

Life is the art of drawing sufficient conclusions from insufficient premises.
– Samuel Butler