Lin Senhao, a former university student who killed his roommate by poisoning in April 2013, wrote a letter recently to apologize to the victim's parents, just before the second trial in the case was set to begin on Dec 8.

Lin, 28, was a postgraduate student at Fudan University's School of Medicine in Shanghai. He was convicted of intentionally killing roommate Huang Yang with a toxic chemical, and was sentenced to death by the Shanghai No 2 Intermediate People's Court on Feb 18.

Lin's family appealed the verdict and sought a second trial. The letter was disclosed on Monday by Shanghai news website xinmin.cn.