There are quite a few Jack the Ripper Tours available, and so you need to be careful what you book for - however it is well worth doing.
I was keen to find a historical one, as opposed to anything with theatrical tricks/dress etc. For about 1 hour 45 minutes, you're taken around some of the key locations and your guide informs you of the tragic and gruesome events that took place.
I've left the link of the tour I went on which I would recommend:
Location: Starts in Aldgate East