'Jack the Ripper was a murderer in London during the nineteenth century. In those days to put a criminal in prison, you had to catch him while he was doing the crime or get a confession from him. That’s why it was so difficult to catch Jack the Ripper. No one had witnessed any of the crimes. Also, it was such a famous case that many police officers took evidence from the crime scenes as souvenirs. This made it even more difficult to solve the crime. Today there are many films about Jack the Ripper. He is usually played by a middle aged man, even though nobody knows what he looks like.'