Matthew Poole and continuators on Esther 2:23

23 And when inquisition was made of the matter, it was found out, therefore they were both hanged on a tree: and it was written in the book of the chronicles before the king .

This may be referred, either 1. To the writing to note that this was written in the Kings presence by Scribes, who were continually present with the King to write all remarkable passages happening in the Court from time to time. Or, 2. To the book, which was laid up before the King, that he might more easily and frequently peruse it for his own delight or direction.