The Secret of the Long-Lost Cousin & 9 Other Mysteries - Bruce Lansky

Twelve-year-old amateur sleuths, and best friends, Hawkeye Collins and Amy Adams love to solve cases. They invite readers to follow the clues and sketches to solve crimes in their hometown of Lakewood Hills. All of the books in the "Can You Solve the Mystery" series contain 9-10 short mysteries. Readers are given written clues as well as visual clues to help them solve the crime. The answers and a brief wrap-up are given in the back of the book.
The Secret of the Long-Lost Cousin; The Case of the Disappearing Diamonds; The Mystery of the Helpful Professor; The Case of the Daisy Dispute; The Case of the Bouncing Check; The Mystery of the Hardware Heist; The Case of Lucy's Lost Lemonade; The Mystery of the Missing Money; The Case of the Bashed Boss; The Secret of the Ancient Treasure. Part 1: The Black Cave