I know you discount R Michael Gordon's work but, that being said, he quotes some source (the original report possibly) as saying the conductor thought the passenger was "up to no good". Gordon also says that the passenger was not covered in blood so it was probably a false lead (his words). (The American Murders of Jack the Ripper, p. 58)That's sort of putting it mildly.
He isn't actually quoting anyone other than what he read in Edwin Borchard's book. If he had read it in another source, he'd have mentioned the source. He just added the 'up to no good' part because the brief paragraph in Borchard's book makes no mention whatsoever to how the man was behaving.
Of course he would dismiss the hotel key and suggest that the conductor's story was a false lead. He was trying to convince people that his suspect, George Chapman, was the murderer of women in NJ and Carrie Brown...and being Jack The Ripper. Another wasted effort in a field full of financially minded hack theorists
I, personally, don't know what to make of the story the conductor told Det. Kilcauley. It might be true and then again it might be the conductor's reaction to someone out of his typical daily experience.
Since he ultimately dismisses this New Jersey Line train suspect and the whole Danish Farmhand and Damon with the Key, even going so far as to say that the hotel key was never located, he might be reporting accurately from a credible source about what the conductor reported. Well maybe not the not covered in blood part but the in-quotations "up to no good" part which appears to be a direct quote from somewhere presumably said by the conductor."Up to no good" is his invention. Again, if he had read it in a real source, he'd have shared the source. He's trying to push Chapman as the killer, so why not share the source to deflate the conductor's story ?
Read this review in Publisher's Weekly
He's like Melvin Harris with three books of essentially the same
**** ( emphasis on
****) and out for a dollar.
Gordon's third book on the Ripper in four years (after, most recently, The Thames Torso Murders of Victorian London)
is long on speculation and assertion, but short on evidence. He again points an accusing finger at Severin Klosowski, a murderer who used the metal antimony to kill three women. Klosowski was first identified as the legendary serial killer by Inspector Abberline, who had headed the investigation on the ground, and who told the colleague who arrested Klosowski,""Congratulations--you got Jack the Ripper at last."" Abberline never offered any direct evidence that Klosowski was the Ripper, though, and the theory has long been discounted by many, mainly on the grounds that it was highly unlikely that the same killer would have switched from savage mutilations to slow-acting poison. Gordon is unable to offer anything substantive to bolster his case, and, in this volume, his effort to find some proof becomes even more of a stretch, as he expands on references in his earlier works to accuse Klosowski of four murders in New York and New Jersey in the early 1890s.
The author's habit of making definitive statements without identifying his sources weakens his case; one suspects he is simply attributing to Klosowski the unsolved murders that occurred when he was in the U.S. Gordon's own chronology has Klosowski committing his first American murder within hours of arriving in a strange city for the first time, an impulsive act at odds with the Ripper's careful use of his familiarity with the East End to elude detection.
General readers interested either in objective overviews of the known facts or carefully reasoned armchair solutions would be better served elsewhere.https://www.publishersweekly.com/978-0-275-98155-6