Okay. Some guy has announced a book "proving" Vincent Van Gogh was Jack the Ripper, based on a Ripper letter dated 19th July 1889 in comparison with a Van Gogh letter written on 10th October 1888.
Detective Inspector Fran has established:
1. There is no record of a Ripper letter from that date, and only three are remotely accepted as genuine. The From Hell letter, the Saucy Jack postcard, and the Dear Boss letter. Few historians believe any others to be authentic. The handwriting on the From Hell letter does not match Van Gogh's. It is possible that such a letter exists, buried in an archive somewhere, but if no Jack the Ripper websites have mentioned it, it's unlikely to have any significance.
2. Van Gogh was in France, wasted out of his mind, for most of 1888. He had lived around London for a time, but left the UK in 1876-ish and doesn't appear to have ever returned.
3. In August/September 1888, when the Ripper killings occured, Van Gogh was in Arles, France. He was doing a wee doodle called Sunflowers. Gauguin joined him in early September 1888. There's no record of him visiting London during this time.
Here endeth the lesson. *bows*