On 27 September 1888 a letter signed by Jack the Ripper arrived at the Central News Agency. The writer claimed to be responsible for the recent murders in Whitechapel and threatened more. On the morning of 30 September two women were killed. The next day a postcard was received from the same writer, which some thought was proof that he was the killer. Both communications were reproduced and distributed in the hope that a member of the public would recognise the handwriting. Instead, they were inspired to respond with hoax letters.

Whilst these vary in grammar and structure there are patterns. Most followed a humorous tone, mocking the police. The writer boasted about their crimes and indicated that they would carry on. They often referred to recent activity by the police as reported in the media. Only one was regarded as genuine. This contained half a kidney said to have been extracted from one of the victims. Over two hundred of the letters survive and are part of the reason why the Whitechapel murders continue to be studied today.

Researchers have connected their preferred Jack the Ripper suspect to the letters, most notably Walter Sickert.  Senior police officials claimed that a journalist was responsible for starting the craze, even naming him in correspondence. Yet the police investigated a letter received in 1896 as possibly written by the killer. In 1966 it was reported that a different journalist had confessed, in the 1930s. None of these claims are supported by sufficient evidence.

The author of the original correspondence and, thus the creator of Jack the Ripper, remains unidentified.

Paul Williams is a researcher best known for his award-winning book about 333 Jack the Ripper suspects.