Typically an investigation involving a digital crime lab that understands what they are doing. For example tying the digital traces to the actual suspect. If there are no ties to IP addresses or devices then it gets really tricky.

Again in the article the defense is saying the prosecution is demanding the lady prove her innocence, which is something cops love to do.

And because this is a technical crime the fact there is almost no evidence isn't going to save you in a court of law, especially in the 4th least educated state. It's not about the law any longer, but the stories the lawyers weave.