How does the author use foreshadowing in 1st to Die: A Novel?

While Lindsay is searching for evidence, she manages to arrange a meeting with Jenks' ex-wife.... an meeting that seems like a gift from heaven. During that meeting, Lindsay learns that Jenks wrote a book that closely parallels the bride and groom murders, and if she can locate the book, it will be the evidence she needs to get a warrant for his arrest. This foreshadows Lindsay's future attempts to get the book, and as readers, we become sure the conclusion of the case is within her reach.