A case file was evidence in the trial of Soseki Natsume for the stabbing of Olive Green. It contained details on the results of the police investigation of the incident. After Soseki Natsume was charged with the crime, Mael Stronghart assigned lawyer Ryunosuke Naruhodo to the case and had Detective Tobias Gregson divulge the information to him. Naruhodo later visited Briar Road where Scotland Yard was investigating, and Gregson gave him the rest of the details there.
The case file was submitted as evidence at the beginning of Natsume's trial. While cross-examining the two witnesses to the incident, Roly Beate and his wife Patricia, it was explained that the crime had occurred on the beat next to Roly's, with the border between the two beats running down the middle of the road. It would later turn out that Roly had transplanted the scene of the crime from the other side of the road on his own beat.