Who was the thief in the book how come all the best clues are always in the garbage?

In the book "How Come All the Best Clues Are Always in the Garbage," the thief is revealed to be the main character's neighbor, Mr. Smith. Throughout the story, Mr. Smith is portrayed as a helpful and friendly neighbor, but it is later discovered that he has been stealing valuable items from various households in the neighborhood. The protagonist uncovers Mr. Smith's true identity through a series of clues found in the garbage, leading to his eventual arrest and the recovery of the stolen goods.