Because the serial killer known as Jack the Ripper has never been conclusively identified no one can know if he died in the Titanic. The books you speak of are FICTION! After five murders the Ripper stopped. There have been over 100 suspects over the years but none have ever been officially identified as the actual Ripper.
Jack the Ripper was killed in the Titanic trilogy. You can get the story of Jack the Ripper in the most children's literature recently. Gordon Korman included him in his 2011 Titanic trilogy. Jack the Ripper" is the best well known name that is given to an unidentified serial killer. Read more from http://en.wikipedia.org/wiki/Jack_the_Ripper.