Here are some contenders for the title, with their arguments:
* "The Mystery of Marie Roget" (1842) by Edgar Allan Poe: This is considered by many to be the first detective story with a focus on the investigation of a murder. It introduced elements like the use of clues and deduction, which became hallmarks of the genre.
* "The Sign of Four" (1890) by Arthur Conan Doyle: This book introduced Sherlock Holmes, arguably the most famous fictional detective of all time. It solidified many of the conventions of the detective novel, including the use of a brilliant but eccentric detective and a sidekick who narrates the story.
* "The Moonstone" (1868) by Wilkie Collins: While not strictly a detective novel, this book is considered a pioneer of the mystery genre. It features a complex plot with multiple suspects, a missing jewel, and a focus on the investigation.
* "The Notting Hill Mystery" (1892) by Arthur Morrison: This novel is credited with being the first "police procedural" crime novel, focusing on the work of a police officer investigating a crime.
Ultimately, the "first" crime novel is a matter of interpretation and depends on how you define the genre. However, all these works played a significant role in shaping the crime novel as we know it today.