Donald J. Sobol, creator of the popular Encyclopedia Brown mystery series as well as numerous titles for young adults, died on July 11. He was 87.

Leroy “Encyclopedia” Brown was introduced to readers in 1963 with the publication of Encyclopedia Brown: Boy Detective. The intrepid 10-year-old sleuth who helps his chief-of-police dad earned his nickname because he was so smart that he seemed to have a set of encyclopedias in his head.

One of the appealing features of the titles is that they each contain 10 mysteries that readers are encouraged to solve; the answers are located at the back of the book. This formatting idea came to Sobol when he was doing research at the New York Public Library, and a desk clerk mistakenly handed him a puzzle book—featuring puzzles on one side of a page, and solutions on the other—instead of the title he had requested.

Quoted in Contemporary Authors, Sobol once said that his famous character was not inspired by a real boy, but “is, perhaps, the boy I wanted to be—doing the things I wanted to read about but could not find in any book when I was ten.” The Encyclopedia Brown series will celebrate its 50th anniversary next year and Sobol’s longtime publisher, Penguin Young Readers Group, will release his latest mystery adventure, Encyclopedia Brown and the Case of the Soccer Scheme, this October.

Sobol was born in New York City in 1924. He served in WWII with the Army Corps of Engineers and after he was discharged he earned a B.A. degree at Oberlin College. Catching the writing bug via a short-story course at Oberlin, Sobol took a copyboy job at the New York Sun. He later became a journalist for the paper as well as for the Long Island Daily News. But the lure of becoming a book author was strong, and Sobol quit newspaper work at age 30—near the same time he got married—and began writing full-time. The result was more than 80 books for children and young adults, including several works of nonfiction.

In a statement, Steven Meltzer, associate publisher of Dutton Children’s Books, said, “I will truly miss Don Sobol. He was a generous writer who shared with boys and girls a lasting legacy of childhood. In the years I have worked with Don I have met people from all walks of life who have fond memories of his Encyclopedia Brown books and now share them with their own children and grandchildren.”