When the master spy Rudolph Abel was arrested, the inventory of his studios was confiscated. Did the pictures he painted show strategic targets, or were such targets, any kind of site plans, hidden in the hatchings? The paintings were examined, x-rayed, interpreted.
I was interested in the studio as a crime scene, and what it looked like when the FBI got there. I had read about this. It took me almost two years to get copies of the crime scene photos from the FBI archives. They were black and white copies, no greyscale, that's all there was. I couldn't imagine them as useful for crime scene interpretation, but as a basis for interpreting them artistically, as paintings which I made. These were then x-rayed and C-prints were made of them.
See also AMATEUR