Many citizens in the East End weren't satisfied with the progress the police were making and they performed their own investigation, and they patrolled the streets at night. The murders continued. One thing is very clear though, once information from the neighborhood investigation was released, the police definitely did very thorough work and committed a lot of resources into finding the killer. People who claimed the police didn't care because the victims were prostitutes, were very wrong.
Around the middle of 1891 the murders stopped. This is of course highly unusual as these types of murderers don't quit until they're captured or killed. There were also no signs that the murderer ended up moving anywhere else as by 1891 the story of "Jack the Ripper," became an international one so if the same types of killings occurred somewhere else, more than likely they'd know it was the same person.
Of course they never have officially figured out who the killer was although there were around five people out of the hundreds, they investigated who had skills with a knife, but they never could lock the person down. The detailed work the investigators conducted in bringing in people outside of the criminal justice system such as psychiatrists, is in many circles considered the first extensive criminal profiling in a police investigation.
The famous author, Patricia Cornwell conducted her own investigation into Jack the Ripper, and she strongly believes she knows who did it which was a famous British artist by the name of Walter Sickert. If you're familiar with her pedigree, you'd probably believe her like I do. Her story's too good not to tell so I'll work on an article about her to post.