Valkyrie: The Stauffenberg Plot to Kill Hitler, on Operation Valkyrie, which was noted as showing "the advantages offered by a film treatment of a topic" as compared to accounts in print. In November 2012, Isbouts again returned to Biblical history, publishing In the Footsteps of Jesus with National Geographic.Pam Kirsch, "Here are good books to curl up with during 2013", The Vincennes Sun-Commercial (19 January 2013), p. A6. In 2016, Isbouts published two additional books, Archaeology of the Bible: The Greatest Discoveries From Genesis to the Roman Era, also with National Geographic; and Ten Prayers that Changed the World. A 2020 Houston Chronicle article noted that "Isbouts has two main passions: the message of the historical Jesus and the artists who shared and represented those sentiments". A musicologist, Isbouts also produced recordings for several of his films. Investigations of the Mona Lisa and Leonardo da Vinci In October 2013, Isbouts published another book examining a Renaissance art theme, The Mona Lisa Myth, examining the history and events behind the Mona Lisa in the Louvre and the Isleworth Mona Lisa, endorsing the two-Mona Lisa theory and confirming the latter's attribution to Leonardo. A companion film was released in March 2014, also directed by Isbouts, with narration by Morgan Freeman. Describing his first examination of the Isleworth Mona Lisa, Isbouts related that he was "sceptical but intrigued", stating, "I walked into the vault, it was very cold in there, and I spent about two hours with that painting. But after five minutes I recognised that this had to be a Leonardo". He described being "absolutely floored" by the quality of the preservation and the "intense luminosity of the face". Isbouts presented a theory that the Isleworth Mona Lisa is an earlier work by Leonardo, and is the original portrait of the Florentine subject, "while the Mona Lisa in the Louvre is an allegorical representation of the Madonna Annunziata". He further noted that "24 of 27 recognised Leonardo scholars have agreed this is a Leonardo". In his 2017 book, Young Leonardo: The Evolution of a Revolutionary Artist, 1472-1499, also coauthored with Brown, Isbouts presents a theory that Leonardo also painted two versions of The Last Supper, with the second being a replica of the first painted on canvas at the request of Louis XII of France. In 2019, the pair published The da Vinci Legacy: How an Elusive 16th-Century Artist Became a Global