Mystery, title may be where are you + a name, tween girl detective

I used to reread this book all the time when I was younger. It started out with a girl finding a purple wallet in a stairwell and seeing a woman's hand with a ring on it. She lives at the shore, she finds a note in the wallet saying something about killing someone...she brings her best friend into her investigation whose name was Potsy or something, who doesn't like to swim...During her investigation she finds a dog, she goes under the boardwalk, she goes to a fortune teller and for some reason the fortune teller pretends to die? using red ribbon? and the girl freaks out and gets a police officer or some thing but there's no evidence of murder...and at the end the fortune teller was just filling in for her aunt or something and she broke a special shell and had to find a new one....and the note was all a big misunderstanding....

I'm sorry this is so garbled. I'm just putting down random things I remember haha.

Just kidding. I remembered, It's Loretta P. Sweeney, Where Are You? by Patricia Reilly Giff

Loretta P. Sweeny, where are you? by Patricia Reilly Giff? Can't find too much info about it, but the cover on Amazon shows a fortune teller and there's a blurb reading:

"A determined crime-solver, Abby finds a purple and orange wallet that she thinks may belong to a murderer, and seeks to find him."

Crazy...simultaneous posting, there.

Weird!

It's amazing how often putting down what you remember about a book will bring up its name. It's worked that way for me at least twice - once I remembered after I posted and once before I clicked Post message.