Recently, tests have proved that Beethoven died from lead poisoning. Bill Walsh directed the Beethoven Research Project. Mr Walsh and his team examined pieces of bone belonging to Beethoven. They found a large amount of lead in the bone pieces. They said the lead levels were equal to those found in pieces of his hair in earlier studies of other scientists. Genetic tests proved the bone pieces and hair came from Beethoven. The researchers also examined bone fragments( from someone else who lived during the same period. Both were from the top of the skull. The fragments from Beethoven had more lead than those from the other person. Their study didn't find measurable levels of cadmium   or mercury  , which scientists used to consider were the causes of his health problems. Beethoven was sick for much of his life. He experienced strong stomach pains, a sign of lead poisoning, and a change of personality when he was around 20. He also got angry easily, and suffered from depression and hearing loss. His health problems became worse as Beethoven grew older. Walsh said the lead levels found in Beethoven's skull  suggested the metal might have been present in his body for many years. He said although there had been recognized cases of deafness caused by lead poisoning, there was no strong evidence to suggest that lead poisoning was the cause of Beethoven's deafness. Ludwig van Beethoven visited many doctors to find a cure for his health problems. In a letter he wrote to a friend, he asked researchers to examine his body after he died so that other people would not have to suffer as he did. During the research, Walsh and his team didn't    _   .
examine the bone pieces of Beethoven examine the bone pieces of another person examine the lead levels of Beethoven's hair measure the cadmium or mercury in Beethoven's bones