Tianle Li poisoned her husband with thallium obtained from the lab where she worked
A chemist in the US has been found guilty of killing her husband with thallium obtained from the Bristol-Myers Squibb (BMS) lab where she worked. Tianle Li, 43, was also found guilty of hindering her prosecution after originally claiming that she did not have access to thallium at BMS.
During the trial, testimony revealed that Li had obtained four bottles of a thallium salt from BMS in November 2010, before returning three later that year. In the US the general public cannot purchase thallium but it can be useful in the chemistry lab, for example its salts can help promote cross-coupling reactions. However, thallium is also known as a perfect poison – odourless, colourless and tasteless, and less than a gram can be deadly.
On the 14 January 2011, Li’s husband Xiaoye Wang checked himself into University Medical Centre in Princeton with flu-like symptoms. It was not until several days later that thallium poisoning was suspected and a urine sample sent for testing. To do that the sample had to be transferred to a lab in another state.
The actual test for thallium is quite simple, says Barry Samson, director of the trace element laboratory at Charing Cross Hospital in London, UK, explaining that he uses inductively-coupled mass spectrometry on blood or urine samples. However, he adds, not all labs have the equipment and although, in this case, thallium poisoning was suspected, checks for the metal will not always be carried out in scans for heavy metals if there is no suspicion that the patient has come into contact with the element.
Wang died in hospital on 26 January 2011, just one day after doctors received the results of his tests. Curtis Rykal, a lab technologist at the Mayo Clinic in Minnesota who tested Wang’s urine for thallium, told the court that the results ‘were higher than our highest reportable amount. It was off the charts, I have never seen results that high.’
Thallium is so poisonous because the body confuses it with potassium and so interferes with numerous processes, causing nerve damage. Thallium poisoning can be treated with Prussian blue, however in Wang’s case staff at the hospital were not able to get any to the hospital before he died.
Tianle Li will be sentenced later this year and is facing life in prison for the crime. BMS were approached by Chemistry World for comment but they declined due to pending civil litigation related to the case.