The fate of Louis-Charles, son of the last king of France, was for years shrouded in rumour.
The little boy was said to have died in prison in 1795. But for years, rumours spread that he had been swapped with an imposter.
It wasn't until a team of scientists took DNA samples from the heart of the imprisoned boy in 2000 that the mystery could be laid to rest.
In 2021, Prof Jean Jacques Cassiman and historian Deborah Cadbury told Claire Bowes about the extraordinary tale.
(Photo: Drawing of Louis-Charles being separated from his mother Marie Antoinette in 1793. Credit: Universal History Archive/Universal Images Group/Getty Images)