Best was allegedly a freelance reporter working at the The Star at the time of the Jack the Ripper slayings which terrorized London in the fall of 1888. He claimed responsibility for the "Dear Boss" letter, the first to be considered by Scotland Yard as anything other than a hoax, after its claim that the next victim would have her ear cut off was partially realized in the death and subsequent mutilation of Catherine Eddowes. This letter was also the first to use the name "Jack the Ripper", which has since become the most recognized name for the killer.
Best apparently confessed to being the original author of this letter in 1931. He claimed that he had written it in order to maintain interest in the case and sell more newspapers. This confession was not revealed until 1966, when Crime and Detection identified him as the self-confessed author of the letter, as well as a number of other letters that were published in the contemporary press. There is no substantiation for his claim, nor is there evidence against it.
Best appeared as the author of the "Dear Boss" letter in Eddie Campbell and Alan Moore's From Hell, where he was portrayed as an enterprising reporter who wrote the letter and created the Ripper name in order to stir interest in the case.