The kind of narrator is the first person narrator and he was the juryman.
The settings are 15 Northwood Street, murder trial’s place and Laurel Avenue (when another witness saw Adams). The most important characters are Mr Adams, Mrs Salmon and Mrs Parker. The secondary characters are Henry McDougall, Mr Wheeler and another witness. The climax and the turning point of the story were when Mrs. Salmon saw Adams with his twin at the murder trial. There was a lot of suspense. The story is what the author has in mind, but in this story there is also the plot, because the narrator immediately said that it happens a murder. This is a crime story because we know the murderer from the
beginning.
And also something about Divine Vengeance in the story - Divine vengeance is the main essence of the uncanny classic, "The Case for the Defence", by Graham Greene. Initially, in the story, Greene presents forth that at least one of the Adams are certainly the murderers. This can be understood clearly by the number of evidences (witnesses), and the manner of writing of Greene. The scene yet plays loopholes and ultimately both the Adams escape without any of them held guilty. This is certainly against the “DIVINE JUSTICE”. It is obvious that when things get beyond the hands of we mortals, the spiritual Lord does justice. After the twins escape human justice, one of them ends up being killed by a bus. This is not elaborate to any great extent as it gives the story a sinister appeal. Hence, to answer your question, this is a clear cut example of divine vengeance.