Everyone gets robbed from time to time & to find the thief may require a little magic. For this purpose I recommend either Book & Key or Turning the Loaf.
Book & Key
This method was commonly used from medieval up to the 19th century. Keys used to have hollow ends. You need one for this divination.
The names of suspects are written on slips of paper & inserted one at a time into the hollow end of the key which is held between the pages of a book. When the guilty person’s name is inserted into the key, the book will move or even fall out of the hands of the person holding it.
Turning the Loaf
Insert 4 knives into the sides of a loaf of bread. Then sink a peg into the middle of the loaf so it balances like a spinning top. Recite the names of the suspects & the loaf will turn at the name of the thief.