>The fact that they just need a few photos relating to one incident is irrelevant. To preserve them as evidence they will have to do a forensic extraction that can't be questioned (e.g. photoshopping) in court. Typically they will also look for evidence of any other crimes, because there is always some. Even if it's just a dodgy banner in the browser cache somewhere, they like to throw a few random child porn or terrorism charges in too, as punishment.
This has never happened, though. It's just web page comment filler. There are enough problems with the legal system without inventing anything.