I read Patricia Cornwall's novel on the subject a while back (Portrait of a Killer: Jack the Ripper - Case closed). By using modern forensic techniques, she decided on eccentric artist John Sickert as being Jack the Ripper. She concentrated on letters he sent to police and his art works. I always thought her case was unconvincing and would not stick up in a modern court.
Here's a turn up for the books. Author John Morris asserts that Jack the Ripper should actually be Jacqueline the Ripper. According to the article, he built a good case to support his assertion. Royal Gynaecologist Sir John Williams was always a suspect, but it now seems as his wife had the motive. He had an affair with one of the last women killed. Lizzy Williams could not have children, and had lost her family fortune. She was desperate and would hold on to her man at any cost.
It was always assumed that the crimes were committed by a man, but a woman would also have been able to do similar damage with a scalpel without much effort. The strongest evidence for his theory is the burnt woman's clothes in a fireplace of one of the victims. The investigators always assumed it was the victim's clothes. He now says it was the murderer's clothes. Later on a witness reported seeing the victim. It was the murderer fleeing the scene with the victim's clothes. Up to this day similar crimes, e.g., cutting out the uterus, have been committed by women mostly.