Stefan Petrucha.
Titles I've written about:
Ripper (2012):
While the descriptions of the original Ripper murders are gruesome, which may put off the squeamish, they're brief and infrequent, and the book is much more a detective-adventure story than a crime novel. It also straddles the line between middle grade and YA, so be sure that your more mature middle-grade readers don't miss it, especially if they're into adventurous historical fiction and/or mysteries.