SHANGHAI - A postgraduate from a renowned Shanghai university described the murder of his roommate with lab poison as an "April Fool's trick" as his high-profile trial opened on Wednesday.

Shanghai No. 2 Intermediate People's Court heard the case of Lin Senhao, whose alleged murder of Huang Yang in April prompted a national outcry and soul-searching on the moral education of Chinese youth.

The covered-up dead body of student Huang Yang is taken to the morgue of Zhongshan Hospital in Shanghai, April 17, 2013. [Photo by Zhang Ruiqi/Asianewsphoto]

Lin, a medical student at Fudan University, admitted that his act caused Huang's death and dealt hefty blows to his family, adding that he would accept any punishment issued by the court.

Lin denied being on bad terms with Huang, whom he described as smart but conceited. He claimed the poisoning was a spur-of-the-moment act after hearing Huang talk about April 1 being a day of pranks.

"April Fool's was coming, and Huang Yang said he planned to play tricks on others, so I thought, fine, I will give you one first," Lin said.

Police said Lin used N-Nitrosodimethylamine, a deadly chemical compound he took from the university lab, to contaminate a water dispenser in their dormitory on March 31. Huang drank from the dispenser on April 1 and died of organ failure days later.

Doctors initially could not determine the nature of Huang's sudden symptoms until a student made an anonymous text message suggesting Huang was poisoned.

Police arrested Lin in late April and pressed the charge of intentional homicide.

At Wednesday's trial, Lin confessed to the poisoning, saying he was inspired by the poisoning case of Tsinghua University student Zhu Ling, in which the criminal was never caught.

But Lin said he did not intend to kill Huang, only to "make him suffer," adding that "the majority of guinea pigs survived" his experiments with N-Nitrosodimethylamine.

Several classmates of Huang and Lin also testified at the trial, describing Lin as an introverted man prone to bear grudges, and that the two had disputes over a few trivial issues.

Huang's murder trial received national attention as experts and the public questioned the lack of moral education behind the the extreme act of a promising medical student.

"China's test-oriented education has failed to teach children to respect the law and life," said Yin Xiaohu, a legal expert at Shanghai Academy of Social Sciences.

Sociologists said another alarming trend is the worsened psychological state of Chinese students, as they struggle with mounting pressures and inadequate counselling services on campus.

"Many college students are spoiled single children who have problems coping with their emotions when facing fierce competition in schools," said Huang Hongji, director of the Shanghai Youth Research Center, who noted that many cases of conflict or mental distress reported by today's students were caused by nothing but trivialities.

The tragic story of Huang also helped train the spotlight on the case of Zhu Ling, a chemical major at Tsinghua University who suffered severe brain damage after being poisoned with thallium in 1994.

Zhu's roommate was suspected to be responsible, but charges were never pressed and the case remains unsolved. Huang's case, however, rekindled discussion of Zhu's case, forcing Beijing police in May to respond to speculations that her roommate's family used its influence to hinder the investigation.