Those words, preserved in the Jack The Ripper case files and penned by Inspector Macnaghten have been enough to condemn the otherwise obscure Druitt as Jack The Ripper in the minds of many students of the case.
In fact, as modern research into his life has uncovered more about him than the police themselves knew at the time, the actual evidence connecting him to any of the murders has become conspicuous by its absence. Whatever 'private information' may have existed against him has been lost - if it ever made it into the official case files in the first place.
So what do we know about this apparently well to do barrister and teacher who left his home at 9 Eliot Place, Blackheath to take his life one November evening in that long-ago Autumn of 1888?
Born into a reasonably affluent medical family in Dorset, Druitt's early life was coloured by privileged education. He attended both Winchester (then as now an elite establishment) and from there went on to attend Oxford through a scholarship, wherein some of his course fees were paid through a fund.
The scholarship was intended to recognise academic potential, but Druitt left Oxford with only a third class honours degree in Classics. Coupled to his documented interest in sport, modern biographers have speculated that perhaps his zeal for academia faltered as he became more interested in sport.
Following his graduation, Druitt took up a teaching role at privately owned school in Blackheath and joined Morden Cricket Club. In 1882, he had evidently decided on a future career and enrolled at the Inner Temple to study for the Bar in order to become a solicitor or lawyer.
Why was he a suspect?
Of course we know him today because of Macnaghten's note quoted above. In it, he avers to 'private information' that lead to Druitt's addition to the list of suspects. What precisely that information was is lost to history, but Macnaghten clearly states that it came from Druitt's own family. There is also the allegation that he was "sexually insane." In the context of 1888, this is likely to mean that he was suspected of being homosexual.
It is possible that the suggestion of homosexuality was enough to mark him as a suspect. Inspector Littlechild told reporter George R. Sims in a letter of that: "It is very strange how those given to 'Contrary sexual instinct' and 'degenerates' are given to cruelty". In the context of the letter he was discussing another suspect - Francis Tumblety - who was known to be gay.
Perhaps, like the "Jewish madman" theory, the idea that the murders could be the work of an outwardly normal member of society was alien to the Victorian detectives and so it was that suspicion was directed at the likes of Druitt merely because there was a whiff of sexual difference about them. Without access to the 'private information' in which Macnaghten placed so much importance it is unlikely we will ever know more.