I know some comments are speculative on "just 5 murders", but it was the method he did them in that put terror into everyone's heart at that time in life. The bodies were found mutilated and strewn about, like a horror movie. Of course murders and death happened during this period, however this was the first infamous serial killer that went public in a way. Newspapers were the main source of media so they printed puff piece after puff piece, adding to the terror. Hundreds if not thousands of people were interviewed by the police but nothing came up. 4 main suspects are still theorised to be Jack to this day, inconclusive sadly.