The key word: Almonds **spoilers**
Read a few posts and people, I think, are not really getting the end. In an early meeting with the FBI, Kraus's character says the liquid in the suspect's kitchen smells like almonds. The FBI blows this off as flavoring. In the final scene of the movie, the broadcast mentions cyanide. Cyanide is known for having a "bitter almond" smell. This is perhaps the smartest thing in the film, that the writers would drop that off so much earlier but complete the tie right at the end, unnoticable to most.
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