Dr. Walther Parson, who led tests on the skull, said in a documentary about the project called Mozart: The Search for Evidence, "For the time being, the mystery of the skull is even bigger."

Analyses by the Institute for Forensic Medicine in Innsbruck and the U.S. Armed Forces DNA Identification Laboratory in Rockville, Maryland, proved inconclusive, said Parson. Researchers planned to compare the genetic material in the skull to two sets of bones believed to belong to relatives of the composer. But tests on the two sets of remains showed that they were not related to each other.

The skull, which is missing its lower jaw, has been in possession of the International Mozarteum Foundation in Salzburg since 1902. Mozart died in 1791 at age 35 and was buried in a pauper's grave in Vienna.