By David Chazan
BBC News, Stockholm
It is a centuries-old whodunnit which could now be solved by modern science.
Charles XII was a colourful figure who loved soldiering
Ever since Sweden's King Charles XII (Karl in Swedish) was killed in 1718 while leading an invasion of Norway, there has been a debate over who shot him.
Was he felled by a Norwegian bullet - or was he assassinated by one of his own soldiers?
Now Swedish scientists want to exhume the king's remains and use advanced technology to solve the historical mystery.
Charles XII was a controversial warrior king.
X-rays show a gaping hole in the king's skull
It is thought that he became unpopular because he led Sweden into a series of foreign military adventures while the country lost control over some of its territories.
Because of that, some historians lean towards the theory that he was killed by a Swede.
"There's huge historical interest in who shot him," says Stefan Jonsson, a material science professor at the Royal Institute of Technology in Stockholm.
Prof Jonsson is one of the researchers hoping to be given permission to remove the king's remains from his tomb in a Stockholm church.
It is the oldest standing building in the capital and houses the tombs of some 17 other Swedish kings and queens.
Prof Jonsson hopes to crack the royal murder mystery
"Today, we have much more sophisticated and accurate methods of analysis and we want to use them to examine traces on the bone fragments from around the bullet hole in the skull," Prof Jonsson said.
He wants to take a sample of bone and use an electron microscope to analyse traces of metal which are likely to be present.
"Even if there are only tiny traces, we'll be able to tell their chemical composition," Prof Jonsson said.
"This is a sort of criminal technical investigation, using some of the techniques which forensic scientists use at crime scenes today."
Prof Jonsson says there was a superstition at the time that the king could not be killed by a normal bullet.
If one of his own officers had wanted to assassinate him, he might have had a brass button from a Swedish army uniform re-made into a bullet so he could be sure that the king would die, historians say.
X-rays of the king's embalmed remains show a gaping hole in his skull, leaving little doubt that he died on the spot.
Charles XII was a colourful figure who loved soldiering.
King Charles XII was buried in a Stockholm church
During his many campaigns, he is said to have endured the same privations as his men, sleeping on the ground and wearing simple military clothes.
The uniform he had on when he died in Norway now hangs in a Stockholm museum near the Royal Palace.
It bears no sign of rank, although the cloth is of exceptionally fine quality.
The fatal bullet hole can be seen on the left side of his hat and bloodstains are visible on his gloves.
DNA tests have indicated that it is probably the king's blood.
Early in his reign, Charles XII led some brilliant military campaigns but he made a disastrous decision to invade Russia in 1708.
His army was routed and he fled to Turkey.
Historians say his failures in that and other wars cost Sweden its rank as a great power.
When his sister succeeded him, she was forced to agree to a new constitution which handed much of the monarchy's power to the nobles and clergy.
Prof Jonsson and his colleagues now want to lay to rest the speculation about who killed him, but they have yet to receive permission to disinter his remains.