One of France's most enduring mysteries will be officially laid to rest next Tuesday, when the presumed heart of King Louis XVII will be officially buried outside Paris.

Did France's boy king die of sickness in a cold Paris prison? Was he smuggled out of the country to later become an environmentalist in America or a clockmaker in Germany?

For years, the mystery of France's so-called "lost dauphin" spawned a crop of conspiracy theories - not to mention dozens of false claims to the French throne. But there are a few indisputable facts about young Louis Charles, son of French King Louis XVI and Queen Marie Antoinette.

When Louis XVI was beheaded in 1793 at the height of the French revolution, the 8-year-old boy technically inherited the royal crown. Young Louis XVII was incarcerated in a Paris prison at the time and, according to some historical records, died of tuberculosis two years later.

Historian Jacques Charles-Gaffiot says a French doctor who performed the autopsy on the young monarch took the boy's heart home as a souvenir.

Mr. Charles-Gaffiot says the doctor put the king's heart in a container of alcohol, where it stayed for years. It was stolen and returned. Eventually it was sent to descendants of Louis royal Bourbon family in Spain. Ultimately the preserved and dried organ returned to France and was placed in the basilica of St. Denis outside Paris, where other members of the French royalty lie.

But it was only until four years ago when DNA testing confirmed the heart matched genetic data of the young king's mother, Marie Antoinette. Late last year, a group of French historians published a report backing up the scientific conclusions.

The centuries-long uncertainty over Louis XVII produced dozens of pretenders to the royal throne. A native American Indian claimed he was the true French king. So did a German clockmaker, whose 1845 death certificate ascertains he was Charles Louis de Bourbon, or Louis XVII.

Even today, the debate is not over. The family of the German clockmaker disputes the DNA findings and hang onto the royal claim.

But for members of the royal Bourbon family, like Prince Michel de Bourbon de Parme, the young king's odyssey is over.

Speaking to reporters earlier, the Prince says Louis' heart will be buried alongside his parents' remains. The ceremony won't be a funeral, he says, but a deliverance for the lost king.