This is the case of the mysterious death of Ricky McCormick with lots of rabbit holes to go down to and the case is still unsolved to this day. FBI has released cyphered Notes left behind in Ricky‘s pocket and the notes have still been unsolvable. Sources:

https://www.stltoday.com/news/article_bcc02074-5b1a-11e0-b199-0017a4a78c22.html

https://www.nytimes.com/2011/04/01/us/01code.html?scp=1&sq=ricky%20mccormick&st=cse

https://thetruecrimefiles.com/ricky-mccormick-murder/

https://m.riverfronttimes.com/stlouis/code-dead-do-the-encrypted-writings-of-ricky-mccormick-hold-the-key-to-his-mysterious-death/Content?oid=2498959

https://www.fbi.gov/news/stories/help-solve-an-open-murder-case-part-2

https://www.esquire.com/entertainment/a33526012/unsolved-cold-cases/

https://ciphermysteries.com/2013/03/12/ricky-mccormicks-two-mysterious