Never trust the author
Borges’ use of prolepsis at the start of the story does one of two things. Firstly, it introduces us to Lonrott as a decently capable detective as he is able to figure out when one of the murders is, however, he isn’t able to stop it. Secondly, it provides a brief overview of the conclusion of the text, but with very few details, so it keeps the readers from knowing the whole truth. The use of prolepsis causes the reader to expect Lonrott to solve the crime, increasing his credibility, as well as create anticipation and suspense about the end of the story.
After recognizing these two facts, it led to me reading the text with a lot of trust in Lonrott, so I didn’t pay much attention to his intense research into Jewish practices and holidays. It also made me read the text carefully to try and figure out the conclusion before it was fully revealed to the reader. It became a competition between the text and myself, as I knew what was going to happen, but I wanted to figure out how before it was unveiled by Borges. Each detail and fact that was thrown at me was analyzed and taken note of to try and piece together a truth that would eventually solve the case. Unfortunately (but fortunately because it made it more interesting), Borges offered us a solution that was much more complex than we might have expected. Well, not exactly much more complex because the start of all the murders ended up being just as Treviranus had predicted. As the readers, we are thrown off not only by Lonrott being the last murdered person but also by the fact that he was wrong all along despite the long explanations and discoveries we are told about.