He dropped the film off at Walgreens the day before the massacre.
Perhaps the most surprising part of that is the use of film. Don't most people use digital cameras now, and doesn't anyone taking naked/embarrassing pictures of himself go digital? It must be that Loughner wanted to involve real people in the process of discovering these photographs of the killer clowning with the gun at the very time he was using the gun on a murder spree. It was another way to inflict pain, and he went to some trouble to do it.
Isn't this evidence useful to the prosecution? It shows elaborate planning, I think, including perhaps a plan to appear crazy. Why go to the trouble and expense of using film? Did he not try to time the development of the photographs with the massacre? Or do you think posing with the gun like that makes him seem more crazy and is useful to the defense?