In the past 125 years, there have been more than 100 names mentioned as possible suspects - 100 different names that have been accused, at some point or another, of committing the heinous crimes of Jack the Ripper. One of the most well-known suspects is named Aaron Kosminski.
While no one can know for sure, experts can make informed guesses about Aaron's background and childhood that would make him a perfect fit to the psychological profile of a sexually motivated serial killer. There is little, if any, physical or circumstantial evidence that ties Aaron to the murders.
Aaron was Jewish, very poor, and born in Russia during the 1860's. Anti-Semitism in Russia was very high during his youth, and perhaps was the reason that his family left Russia around 1881. From 1881-1884, there were more than 200 anti-Jew mob attacks in Russia, called "pograms" in English, during which many Jewish women were raped as a part of the violence. There is a strong possibility that a young, impressionable Aaron could have witnessed the rape of his sisters, mother, or other female relative or friend during this time. Witnessing or experiencing sexual violence can make an unstable person more likely to commit similar crimes.
There are other factors that make Aaron an ideal fit for the profile of a serial killer, such as the injustice he undoubtedly experienced as a Jew in Russia. Also, unstable residency during his youth, possible lack of a father figure, and unstable work history work against the case for his innocence. Despite the theory that he fits the bill of a serial killer quite well, there is no actual evidence that he was involved in the murders. In fact, he never fit the physical description of the killer given by many different eye witnesses. Aaron lived for more than thirty years after the murders ceased.