Confession of Lawrence Wargrave

A manuscript is found in a bottle washed ashore, written by Lawrence John Wargrave. In it, he confesses to being the mastermind behind the entire plot. He reveals that he is terminally ill and wanted to commit the perfect crime, executing those who had escaped justice. He describes how he faked his own death, manipulated the others, and killed them one by one according to the nursery rhyme. He explains how he used Armstrong as an unwitting accomplice, then drowned him. He staged his own suicide to appear as a victim. The confession solves the mystery, revealing that the judge was the killer all along.