New Tests on Tilly letter prove it genuine – Casebook: Jack the Ripper …

No, the letter was not worth a second look (in my opinion) but I also knew from bitter observation that even bad Ripper hoaxes tend to have longevity, so I thought it would be advisable to contact the seller and ask for clarification on a few points and get them down on record. What I heard did not calm my initial suspicions.

https://forum.casebook.org/forum/ripper-discussions/suspects/kosminski-aaron/844031-new-tests-on-tilly-letter-prove-it-genuine/page2