The "Dear Boss" letter, from September 25, 1888. On September 29, a Central News Agency journalist, Tom Bulling, forwarded a letter to the Metropolitan Police which he said had been received by the agency two days earlier. At first it had been "treated as a joke." The letter claimed to be from the killer and was signed "Yours truly, Jack the Ripper." Its prediction of events to come was particularly chilling.
The National Archives