This letter dated dated 23rd Sept 1913, was written by Inspector , head of Special Branch.It talks of Littlechilds suspicion of a Doctor. (Almost certainly Francis Tumblety)
In part, Verbatim.
"I never heard of a Doctor D, in connection with the Whitechapel murders, but amongst the suspects, and to my mind a very likely one, was a Dr T (which sounds much like D.) He was an American quack called Tumblety and was at one time a frequent visitor to London, and on these occasions constantly brought under the notice of the Police, there being a large dossier concerning him at Scotland Yard. Although a "Sycopathia Sexualis"(Sic) subject, he was not known as a sadist, which the murderer unquestionably was, but his feelings toward women were remarkable and bitter in the extreme,A fact on record. Tumblety was arrested at the time of the murders in connection with unnatural offences (homosexual acts) and charged at Marlborough St, he remained on bail, jumped his bail,and got away to boulogne. He shortly left France and was never heard of afterwards. It was believed he commited suicide but certain is it that from this time the ripper murders came to an end..