They did this by comparing the DNA from the preserved heart of the boy with the DNA from known samples of Marie Antoinette's hair. Tragedy struck less than a year later, when Sophie, who had been born prematurely, died. Louis XVII of France (Louis Charles; 27 March 1785 - 8 June 1795) was the King of France and Navarre from 1793 to 1795. Reference Louis XVII (27 March 1785–8 June 1795), from birth to 1789 known as Louis-Charles, Duke of Normandy; then from 1789 to 1791 as Louis-Charles, Dauphin of France; and from 1791 to 1792 as Louis-Charles, Prince Royal of France, was the younger son of King Louis XVI of France and Queen Marie Antoinette. The fate of their son, Louis XVII, however, has been shrouded in mystery for more than 200 years. On June 8, 1795, their son, the Dauphin and the boy royalists had named Louis XVII, died at the age of 10, most likely of tuberculosis exacerbated by his brutal prison conditions. In the summer of 1789, Marie and Louis were devastated when heir Louis Joseph died, aged just seven. Others said the royal heir escaped and that another child died … Louis XVII would have been King of France after the beheading of his father Louis XVI but for the fact that France was a republic at the time. Some historians declared the dead child to be Louis XVII. The future King Louis VXII was born on 27 March 1785, the second son of King Louis XVI of France and Queen Marie Antoinette, and named Louis-Charles. The fate of Louis XVI's son had long intrigued France. On June 8, 1795, Louis-Charles died of tuberculosis in the arms of one of his jailers. Louis XVII (Versailles 27 March 1785 – Paris 8 June 1795), from birth to 1789 known as Louis-Charles, Duke of Normandy; then from 1789 to 1791 as Louis-Charles, Dauphin of France; and from 1791 to 1793 as Louis-Charles, Prince Royal of France, was the son of King Louis … Louis XVI and his wife Marie Antoinette died by guillotine during the French Revolution in 1793. He is also known as Louis Charles, Duke of Normandy and Fils de France (son of France).. Louis Charles of France was born at the Palace of Versailles.He was the second son and the third child of King Louis XVI and Marie Antoinette of France. On April 19, 2000, the Associated Press reported that two scientists were able to determine that the boy, who died at Temple prison on June 8, 1795, was Louis XVII. It is a mystery that has lingered since the 18th century: did King Louis XVII of France really die in prison in 1785 or did he escape to found a new royal line? The case is puzzling to this day, and conflicting evidence is offered from likely or unlikely sources. He never actually ruled. He died while imprisoned in Paris; or maybe he didn't. When his older brother, Louis Joseph, died of tuberculosis on 4 June 1789 when he was only seven years old, the four year old Louis Charles became the Dauphin and heir to the throne. He was only ten years old.