( CNN ) -- A man pleaded guilty Monday to killing a Virginia Tech graduate student at a restaurant in January , attacking her with a knife and decapitating her , according to officials . Haiyang Zhu , 26 , pleaded guilty to first-degree murder in connection with the death of Xin Yang , a graduate student studying accounting at Virginia Tech , officials said . Xin , 22 , from Beijing , China , had begun her studies at Virginia Tech only two weeks before she was killed at the Au Bon Pain restaurant in the university 's Graduate Life Center on January 21 , school officials said . School spokesman Larry Hincker told CNN in January the two were believed to have known each other , based on emergency contact records maintained by the university , but witnesses saw no sign of an argument before Xin was attacked . Haiyang , a native of Ningbo , China , was taken into custody at the scene . He had written a love letter to Xin , but she told him she was engaged to another man , Montgomery County commonwealth 's attorney Bradley Finch told CNN . Haiyang purchased the knife used to kill Xin the morning of her death and attempted to call her 12 times , with the first call coming just after he bought the knife , Finch said . `` He completely severed her head , '' Finch said . Xin also had severe knife wounds to her hands and arms , he said . In a writing titled `` Will , '' Haiyang said he had expressed love for Xin and that she broke his heart when she said she was engaged to someone else , Finch said . Haiyang said the rejection was too cruel and that Xin 's fiance could not compare to him in education and background , and she should have seen he would be the best husband for her . Haiyang was a graduate student pursuing a doctorate in agricultural and applied economics . Hincker said he began studying at Virginia Tech in the fall of 2008 . Haiyang is scheduled to be sentenced in April , according to court records . Xin 's slaying was the first on the Virginia Tech campus since April 16 , 2007 , when Seung-Hui Cho killed 32 students and professors before turning a gun on himself . CNN 's Carolina Sanchez contributed to this report .
Haiyang Zhu pleads guilty to first-degree murder in the death of Xin Yang . Xin was attacked with a knife and decapitated at a restaurant in January . They were believed to have known each other , but there was no sign of an argument . Slaying was the first on the Virginia Tech campus since the 2007 shootings .