The answer to that question may be at hand.
"The great-great nephew of an Austrian doctor who acquired several fragments of what was thought to be Ludwig van Beethoven's skull in 1863 said recently completed tests show a high likelihood that the bones he inherited 15 years ago belonged to the great composer." Read the rest here.
Tests indicate that the skulls bones are indeed Beethoven's. Details. More info here.
See pictures of 'em here. A reproduction from them of entire skull can be seen in a foto in this article.