Just a week after a Chinese graduate student at Queen’s University in Canada received a seven-year prison sentence for repeatedly poisoning his former roommate and fellow chemist with the carcinogen N-nitrosodimethylamine, a similar incident has emerged in the US. In the latest case, Yukai Yang, a 22-year-old chemistry major formerly at Lehigh University in Pennsylvania, who is also from China, was accused of poisoning his roommate with thallium and possibly other chemicals.

Yang, whose visa was revoked and is not enrolled at the university anymore, was charged with attempted homicide, aggravated assault and other offences, local district attorney John Morganelli announced on 20 December. Victim Juwan Royal’s blood was found to have 3.6μg/l of thallium in it – high enough to make him seriously ill. Yang has reportedly been previously charged with vandalism of Royal’s property with racist graffiti.

When administered in large or frequent quantities, thallium can damage the nervous system, lungs, heart, liver and kidneys. The chemical was initially suspected in the poisoning of former Russian security agent Alexander Litvinenko.

Royal, who graduated from the university but continues to suffer the physical after effects of the poisoning, had symptoms that were consistent with thallium poisoning, including vomiting and diarrhoea.

‘Mr Yang, who is a chemistry major, admitted to purchasing various chemicals through the internet, including thallium, and stated they were purchased with the intent to harm himself if he did poorly on future exams,’ Morganelli said at a press conference. ‘He admitted to mixing these chemicals in with food and drinks which were stored in a community refrigerator that was shared with both he and the victim.’

Lehigh University said its police department is continuing to work closely with Morganelli’s office. ‘From the outset, our concern has been the health and safety of the victim of these alleged behaviours and, as such, Lehigh staff and faculty have been providing support, services and assistance,’ the school stated.