That isn’t how they got her. They noticed there was a crease in the picture, which told them it was printed out.
They looked to see who printed out that document, there were 6 people, and she confessed when they asked her.
Note that they didn’t NEED to see the picture — I’m pretty sure that once they knew the document was out, they would have checked who accessed it, and would have started with the 6 people who printed it out.
So really what outed her was the paper identifying the document so the NSA knew what document to look for.
Not quite.
Whenever any secured doc is printed, all secured printers leave a watermark that is difficult to see.
The watermark is easily spotted by certain scanners, even if it is a copied doc.
She should have known all this, you can make many generations of copies at a private copy center, but watermarks have coding that all private copiers “pass on” to the copies made.
You would have to spot the location of the watermark and physically cut it out of the doc to conceal the origin.
She is busted because she is sloppy, and or a highly motivated moron.