It is a mystery that has gone on for more than a century: did the old skull lodged in an Austrian basement really belong to the greatest composer of all time, Wolfgang Amadeus Mozart?

The results of DNA tests seeking to solve the mystery were broadcast on Austrian TV to coincide with the 250th anniversary this month of the composer's birth. And the answer is: we still don't know.

Last night researchers revealed that Mozart's "skull" - which has been in the possession of the Mozart Foundation since 1902 - had a different DNA result from that of his two "relatives". This could mean either that the skull is a 200-year-old fake or that it is indeed genuine but that the two "relatives" dug up from the Mozart family plot in Salzburg are not from his family at all. The samples from the skeletons of his supposed relatives had different DNA results from each other, leading to suspicions that neither was related to Mozart.

"We got wonderful results from Mozart's skull. Unfortunately the results from Mozart's niece and grandmother don't match with the skull, or with each other," Franz Grabner, from Austria's state ORF television, said last night. "It's still an open question whether we have the right skull."

It is the latest chapter in a story which began in 1801 when a gravedigger, Joseph Rothmayer, purportedly dug up Mozart's skull from a cemetery in Vienna. The composer was buried there in an unmarked grave following his death in 1791 at the age of 35. His skeleton subsequently went missing. But his presumed skull - minus the lower jaw - was handed down to his descendants and eventually given to the Mozarteum Foundation in Salzburg, the town where the prodigy spent most of his life.

In late 2004 researchers from Innsbruck's institute of forensic medicine got permission to dig up Mozart's relatives. They opened the family vault in Salzburg's Sebastian cemetery, discovering nine skeletons and numerous bones, including those of Mozart's father, Leopold, and wife, Constanze.

In the end, though, the hottest leads came from two dusty female skeletons apparently belonging to Mozart's 16-year-old niece, Jeanette, and maternal grandmother, Euphrosina Pertl. "We needed to test the mitochondrial DNA which is passed down the female line," Walther Parson, the forensic pathologist who carried out the tests on the skull, told the Guardian. "We had full skeletons from both of them. Their bones were in rather good shape. We decided to use the femur."

After taking DNA samples, researchers had the problem of how to get Mozart's "skull" from Salzburg to their lab in Innsbruck. "We tried to insure Mozart. But nobody wanted to insure the skull," Prof Parson said.

The Mozarteum eventually transported the skull in a security van used for bank deliveries. Prof Parson and his team then removed two of Mozart's teeth, one of which was sent to a laboratory in the US for comparative tests.

The other tooth was bleached and chopped in half so DNA could be extracted. A professional glued it back together afterwards and put it back in the head. The result arrived in September but was kept secret until the broadcast.

"It's a bizarre story," Prof Parson said. "The skull is now back in the Mozarteum in a locked safe." Had it been worth it, though? "My personal view is that Mozart was the greatest musician who ever lived on the Earth. But I didn't really care whether the skull was real or not."