Can some1 help me find this book Please? (Sadie)?

About 9 years ago,I read a book, I am 95% sure that the name of it was Sadie (named after the name of the town). Anyway, it was a mystery and a really good one. At the end of the book, there was a dead body found but you have to read the sequal to find out about it, I can't find the sequal or the first book for that matter and I've searched everywhere, I'm thinking that the 2nd book was named "Return to Sadie" but Im not sure. Does anyone know about this book or where I may be able to find it? Your help would be GREATLY appreciated, thanks in advance!