Poisoned. But Whodunit?

After months of speculation about the cause of Viktor Yushchenko's grotesquely disfigured face, doctors at a prestigious hospital in Austria presented evidence last Saturday that the Ukrainian opposition leader just like that country's recent election had been poisoned. Tests done during his third trip to Vienna's Rudolfinerhaus clinic showed that the presidential candidate's blood contained such high levels of dioxin a toxic by-product of the manufacture of certain disinfectants and herbicides, and an ingredient in Agent Orange that it was difficult to get an accurate measurement. "The needle was literally off the charts," Rudolfinerhaus director Dr. Michael Zimpfer told TIME, though doctors say his bodily functions are returning to normal.

When the stricken candidate first checked into the elite Vienna hospital in early September, doctors were stumped by his symptoms, which included acute back pain, swollen organs and numerous ulcers lining his digestive tract. But it was his worsening skin disorder, called chloracne, that pointed toward dioxin. Zimpfer noted that the fat-soluble substance would have been easy to administer in a cream-based soup. So who did the poisoning? "Of course, it was done by the authorities," Yushchenko told TIME last week, calling it "an act of political reprisal" by the government of departing President Leonid Kuchma, which supports Yushchenko's rival, Prime Minister Viktor Yanukovych. "All such allegations must be thoroughly investigated," says Kuchma loyalist Volodymyr Sivkovych, who headed a parliamentary investigation that noted that although Yushchenko complained of pains after dining with Ukraine's secret-service chief on Sept. 5, the food had been served on common plates and the drink from bottles uncorked in front of everyone.

As Yushchenko prepares for a Dec. 26 runoff, scheduled by the supreme court after it threw out last month's rigged results, the diagnosis may help consolidate his support and make it more complicated for his opponents to take advantage of his condition. When it was still a mystery, Yanukovych had his top Russian press handler warn voters on TV that if they elected such a sick man, "the very next day Yushchenko will be admitted to hospital."