So ill he could not move, Wolfgang Amadeus Mozart supposedly sang parts of his final masterpiece, "Requiem," from his deathbed. Two centuries later, the exact cause of the Austrian composer's premature death, in December 1791 at age 35, is still a mystery.

Theories abound. It's known that his entire body was so swollen he couldn't turn over in bed; some say jealous rivals poisoned him, while others suggest scarlet fever, tuberculosis, or lethal trichinosis from undercooked pork.

Now, new evidence points to an altogether different conclusion: Mozart may have died from kidney damage caused by a strep infection, possibly strep throat.

Dr. Richard H.C. Zegers and his colleagues at the University of Amsterdam analyzed data from Vienna's death registry. Researchers had not previously analyzed the daily death registry -- begun in handwritten script in 1607 and maintained until 1920 -- for clues to Mozart's death.