While you are probably correct, I am going out on a limb. I suspect the people who were robbed did not know they were going to be robbed. This leads me to believe they did not know their robbers. It seems to me then they couldn’t possibably know what their robbers were thinking and what the robbers knew about the robbery.
That is just as possible as any other scenario, and what the article seemed to imply. The question is ‘now that the hospital has pleaded for the robbers to return the blood, what will they do?”