* The name is misspelled: Perhaps you're thinking of a similar name like "Jonathan Mantel" or "Jonathan Mantle" with a slightly different spelling.
* The author is not well-known: They may be a lesser-known author, and their works are not widely documented online.
* You're thinking of a different kind of work: They might be a writer in a specific niche like technical writing or academic research, where their work isn't easily found through general searches.
To help me find the author you're looking for, please provide:
* Any additional details about the author or their works: Do you know any of the genres they write in, the titles of any books, or any other information about them?
* The source of the name "Jonathan Mantle": Where did you encounter this name? Was it in a book, article, or other media?
With more information, I can try to locate the author you're looking for.