I like your thinkingLong time lurker of the forum, first time poster.
I agree with the posters who thought it was an odd statement from the press conference. It was along the lines of "what is not in a photo can be is as important as what it shows". (paraphrasing here, not a direct quote).
I wonder if a crime scene photo shows something is missing from the apartment? Maybe an item that belonged to one of the victims was taken as a sort of trophy?