I can tell you this from personal experience (professionally) Law enforcement, to include DA’s office’s and Federal prosecutors, won’t touch cases unless it is super clear the children are just that….prepubescent children. They otherwise would lose cases to sympathetic jury’s.
On top of that just having a nude photo of a child isn’t considered child pornography. It has to be a true pornographic photo. Remember this…Springville, NY’s own Penny Baker, Playboy magazine’s 30 year anniversary Playmate, was only 17 years old when her spread was shot.
I don’t mean to be disrectful to you or your police officer friend, but depending on the actual content of what that Principal sent, it very well may not have been distributing child porn.