Read: Portrait of a Killer: Jack the Ripper -Case Closed by Patricia Cornwell. She thinks JTR was an well known artist called Walter Sickert.
Of the half dozen or so Ripper books I've read, hers was, without doubt, the least well-researched and her conclusion that Sickert was the Ripper was based on the flimsiest of evidence. One of the key pieces of "evidence" is that one of his paintings looks a bit like one of the murder scenes, even though his subject is patently not dead. I'm not sure what her motive was for publishing this book, but would hazard a guess it was to further enhance her reputation as an author of a series of novels about a coroner in the US. It's hard to believe she was motivated by a desire to expand the body of knowledge on the subject. AFAIK, not one single serious Ripperologist takes her assertions seriously - that's unique in the field. No one else has zero supporters.