Simplify the following text for a Grade 5 native English-speaking person.
Original: Examples derived from Jack the Ripper include the French Ripper , the DÃ 1\/4 sseldorf Ripper , the Camden Ripper , the Blackout Ripper , Jack the Stripper , the Yorkshire Ripper , and the Rostov Ripper .
Simplified: The letters were signed `` Jack the Ripper '' . Other murders were reported around the same time but were not believed to be the work of Jack the Ripper .