Where do you live?
Is it a document or photo?
While I think I could answer you, this really is a technical question and not a legal question. I'll try to have your question moved to the proper category.
To try to track where a printout came from? The police can essentially investigate anything they like, but if they do so improperly then the evidence is worthless. Try to find out whether this is possible in the first place. A computer expert should be with you shortly.