He is best known for his detective stories, which were published under the pen name Stein Riverton and translated into several languages, including German and English.

After, as a young office boy, embezzling money from his employer, he changed his name and started a new life as a journalist in Kristiania (Oslo).

In 1908 Elvestad (under the pen name Kristian F. Biller) created the police detective Knut Gribb: a character that was taken over by several other writers in various magazines and series of paperbacks, and still exists.

This is a thriller, narrated in a neo-romantic style reminiscent of Knut Hamsun by a guest at a seaside hotel in Southern Norway.

In his latest mysteries, he abandons the Krag character (who was nameless in books attributed to Elvestad) and aims at a more modern, realistic style.