From Hell letter

The "From Hell" letter is the name given to a letter mailed in 1888 by a man who claimed to be the killer known as Jack the Ripper.
Many letters that were claimed to be from the killer were mailed in the time of the Ripper murders. But the "From Hell" letter is thought as one of the few writings from the serial killer. It should be noted that its author chose not to sign it with the pseudonym, "Jack the Ripper", distinguishing it from the earlier Dear Boss letter, the Saucy Jack postcard and their imitators. Also, the "From Hell" letter is written at a much lower literacy level than the other two. It is argued that a person with little or no education would spell words based on what they sound like and as the 'k' in knife is silent, an uneducated man would not likely know that the 'k' was there at all. 
Postmarked on 15 October 1888, the letter was received by George Lusk, then head of the Whitechapel Vigilance Committee, the following day.
The reason this letter stands out more than any other is that it was delivered with a small box containing a human kidney, preserved in alcohol. One of Catherine Eddowes' kidneys had been removed by the killer. Medical opinion at the time was split on whether the kidney was likely to have been the same as the one taken from Eddowes. Some officials thought the organ could have been acquired by medical students and sent with the letter as part of a hoax.
Texts.
The text of the letter reads:
Loss of letter.
The original letter, as well as the kidney with it, have been lost along with other items that were originally contained within the Ripper police files. It is possible that one or both was kept by an official as a souvenir of the case. The image shown here is from a photograph taken before the loss of the letter.