In the Commonwealth Saga, Peter F. Hamilton spends a lot of time describing the universe in great detail. Early in the book, I believe while introducing Detective Paula Myo, he introduces a very outlandish, fringe conspiracy theory that an entity known as the Starflyer was capable of controlling minds and was infiltrating human society. When reading that, I thought it be just background. Turns out I was wrong and the conspiracy was actually true.
So when in The Janus File we hear about the Apple Cypher, I kept imagining that it would be relevant to the plot. I kept looking for ways in which the Apple Cypher could have been part of the crimes -- for example, if the virus could have been delivered to the carriers or to the transceivers via contaminated apples.
I was wrong.
Of course, David Weber is one of the authors and he likes to dangle shiny things in front of us readers to distract from the real threat

I did NOT see the culprit coming, nor how he committed the crime.