Irrational, irritable, hot-tempered: these are all words that have been used to describe the character of Ludwig van Beethoven. His erratic mood swings were more than many could tolerate; profoundly deaf and plagued by long-standing stomach ailments, he alienated even those closest to him, to the extent that the final years before his death in 1827 were spent in lonely, painful torment. Yet a lock of hair snipped from the composer's head the day after his death may hold clues that partially explain his extreme behaviour, especially in his later years. Tests done on strands from the lock at the Health Research Center in Chicago have revealed a concentration of lead 100 times the level expected in people today.

Purchased at auction at Sotheby's in London in 1994 by Dr. Alfredo Guevara, Ira Brilliant and two other members of the American Beethoven Society, the lock is now a central exhibit at the Ira F Brilliant Center for Beethoven Studies at San José State University in California.

Its original owner was Mendelssohn's friend Ferdinand Hiller, who at that time was a piano student of Hummel. Together they had visited Beethoven three times in March 1827 and, on each visit, both saw an increasing physical and mental deterioration:

'On March 13th, Hummel took me to see Beethoven for the second time. We found that his condition had deteriorated considerably. He lay in his bed, seemed to be suffering great pain and at times uttered a deep groan; nevertheless, he spoke freely and vigorously. He seemed to be deeply concerned with his failure to enter the married state. Already during our first visit he had joked about this with Hummel, whose wife he had known as a young and beautiful girl. This time he said to him, smiling: 'You are a lucky fellow: you have a wife, she looks after you, she is in love with you, but I'm a poor bachelor!', and he sighed deeply. Also, he begged Hummel to bring his wife, who had been unwilling to face, in his present state, a man whom she had known at the height of his powers.

'When we stood beside his bed once more on the 20th, it was certainly clear from his remarks how greatly this attention had pleased him; but he was extremely weak and spoke only softly, in clipped sentences. 'I rather think I shall soon be setting out on the upward journey,' he whispered after our greeting. Similar exclamations occurred frequently; but, in between, he spoke of his plans and hopes, neither of which, unfortunately, were to be realised. Speaking of the noble conduct of the Philharmonic Society and praising the English, he said that it was his intention to leave for England as soon as his condition had improved. 'I wish to compose a grand overture and a grand symphony for them.' And then, too, he wished to visit Frau Hummel (who had come with her husband) and go to heaven knows how many different places. It did not occur to us to write down anything for him. His eyes, which during our last visit had still been quite lively, were now drooping and only with difficulty could he sit up from time to time. We could no longer deceive ourselves: the worst was to be feared.'