The letter the detective squad receives that begins "Dear Boss," which Rizzoli is seen holding, is a reference to a letter received the Central News Agency in London, and turned over to Scotland Yard on September 29, 1888. It begins "Dear Boss," and like the letter received by the fictional Boston police, insinuates that the Scotland Yard detectives are pursuing the wrong suspect. The writer also refers to his murders as his "work," several times, just as in the show. The 1888 letter is signed "Yours truly Jack the Ripper." This is how the name "Jack the Ripper" was coined. The detectives in charge of the investigation in 1888 suspected that the "Jack the Ripper" letter was a hoax by a reporter, though, hence addressing the Central News Agency as "Boss."