A team of scientists have said they believe an old gourd contains the blood of French King Louis XVI.
The monarch was killed by guillotine by French revolutionaries more than 200 years ago, on 21 January 1793.
The scientists said the DNA is very similar to genetic material from what is believed to be the mummified head of an earlier French king, AFP reports.
After Louis XVI's beheading many spectators were reported to have dipped their handkerchiefs in his blood.
The piece of fabric had been placed in a dried, hollowed-out gourd, leaving blood stains.
The squash was decorated with images of revolutionary heroes and the words: "On January 21, Maximilien Bourdaloue dipped his handkerchief in the blood of Louis XVI after his decapitation".
The revolutionary souvenir has been in the hands of an Italian family for a century.'Paternally related'
The team of experts from Spain and France has published its findings in Forensic Science International journal.
Analysis of DNA taken from blood traces found inside the vegetable container had already revealed that it probably matched someone of Louis' description but scientists could not prove it belonged to the beheaded king as they had no genetic material from any of his relatives.
However, the team managed to find a rare genetic signature shared with DNA from a mummified head believed to belong to Louis' 16th Century predecessor, Henri IV, who was killed in 1610.
In 2010, scientists said the head belonged to Henri's, saying it shared the same physical features as those illustrated in contemporary portraits of the king.
French forensic pathologist Philippe Charlier told AFP that the study revealed that both of those sampled "share a genetic heritage passed on through the paternal line. They have a direct link to one another through their fathers".
Co-author of the report, Carles Lalueza Fox, of the Institut de Biologia Evolutiva in Barcelona, was quoted as saying that it was "about 250 times more likely that the [owners of the] head and the blood are paternally related, than unrelated".