The name of Macnaghten's second suspect was confirmed as Aaron Kosminiski in the early 1980s when a researcher came upon Donald Swanson's personal copy of Robert Anderson's book of memoirs. Both Swanson and Anderson were officers who participated in the Ripper investigation; indeed, they were the ones given the responsibility of being in charge of the case. Anderson had written in his memoirs that appeared for the first time in 1910 that the police knew who the Ripper was. According to Anderson the Ripper was a Polish Jew who was put away in an insane asylum after the crimes, and then died soon after. Swanson had made some notes in his copy of the book concerning Anderson's suspect, and wrote that the suspect's name was Kosminski. At first it seemed that the case had been solved, but research has found a number of problems with the theory. No other officer supports' Anderson's allegation, and Swanson's notes seem to question his superior's claims rather than support them. Aaron Kosminski was a real person and was placed in an insane asylum. His records show him to be a docile and harmless lunatic that heard voices in his head and would only eat food from the gutter. The dates of his incarceration are wrong, and he did not die soon after his committal but lived on until 1919. Some researchers have tried to explain the problems by saying that the name Kosminski' was confused with another insane Polish Jew, who really was dangerous.
FWIW....
Mike