According to the Associated Press, a former chemist killed her estranged husband by poisoning him with a lethal and massive dose of a highly toxic metal that a nurse''s sharp eye helped identify. Tianle Li, a former employee of Bristol-Myers Squibb Co., pleaded not guilty to murdering Xiaoye Wang by poisoning him with thallium, and hindering prosecution. The plea was entered by her attorney, and Li did not speak during the brief arraignment Wednesday afternoon in front of state Superior Court Judge Michael Toto. According to the prosecutor''s office, Wang, who worked for a computer software company in New York, checked into Princeton Medical Center on Jan. 14 suffering from what appeared to be the flu or some other virus. When his condition worsened, the hospital began to conduct routine tests but didn''t suspect thallium until a nurse remembered a case involving thallium poisoning in China in the 1990s. The 39-year-old Wang had lapsed into a coma by then and died on Jan. 26.