KIEV, Sept. 9 ??“ Ukraine has been testing samples of dioxin from labs in Russia and the U.S. to determine exactly where the chemical used to poison Viktor Yushchneko two years ago had come from, an official said.

Oleksandr Medvedko, the prosecutor general, said only three countries in the world could actually produce such poison, but his comment apparently suggests the investigstors had narrowed the search down to two.