In 1953 Lennart Thanner published a voluminous dissertation called Revolutionen i Sverige efter Karl XII:s död. Thanner concluded, based on his interpretation of events after the King's death, that Charles had likely been murdered. In a footnote on page 366 Thanner mentions a series of rather peculiar letters sent from (mostly) Lund in 1717-1718 by the Chancery official Olof Sandberg (1679-1750). They are written in a peculiar type of "cipher", i.e. the author uses other names for the main characters. The purpose is unclear as it's quite simple to understand who he is thinking of. It's likely they were written like that for amusement rather than for covering up important information or political views. Thanner writes that the archivist Olof Jägerskiöld intended to publish them, but that apprently never happened. So if time permits I will put at least a few summaries online during the next weeks.