If child pron wasn't on the list, then they can't use it to prosecute.
I realize that we no longer live under the rule of law, but when we did that's the way it was.
They found the material after the computers were seized for examination related to the stolen emails. As the article said, when they saw the kiddie porn they got a second search warrant for the kiddie porn. In any event, its like investigating a house murder scene and seeing drug paraphernalia on the coffee table in plain sight. You then get a search warrant to search the house for drugs as you have probable cause.
(I’m not a lawyer but stayed at a Holiday Inn Express last night - not!)