Former Lehigh University student allegedly poisoned black roommate after racist incident Yukai Yang, a 22-year-old chemistry major from China, turned himself to police.

A former Lehigh University student, who was already facing ethnic intimidation charges, is now accused of trying to kill his black roommate with a chemical once used in rat poison.

Yukai Yang, a 22-year-old chemistry major from China, allegedly laced his roommate's food and drinks with deadly chemicals, including thallium, over the course of several months, prosecutors said Thursday.

Authorities say Yang planned to kill his roommate, Juwan Royal, in a slow and discreet manner, but the plot began to unravel in March when Royal started vomiting, shaking and having dizzy spells, authorities said.

Royal managed to make it to a local hospital where he tested positive for thallium -- an odorless and tasteless type of soft metal. It was commonly used in rat poison until the U.S. banned the practice in the 1970s.

"This was over a period of time with small amounts of poisoning occurring," Northampton County District Attorney John Morganelli said during a press conference Thursday. "It was added to food and drinks in the refrigerator.

"We have weird and bizarre behavior on the part of this young man Mr. Yang," Morganelli added.

Royal, who has since graduated, "is still experiencing physical symptoms from this poisoning that occurred," he added.

Yang was already facing an ethnic intimidation charge for allegedly writing racist graffiti in the pair's dorm room in the spring.

“Initially, Mr. Royal was as dumbfounded by this as everyone else, because he believed they had a fairly cordial relationship as roommates,” Northampton County Assistant District Attorney Abe Kassis said. "They were actually roommates for several years during the main fall and spring semesters."

Yang turned himself into police in Bethlehem, Pennsylvania, just east of Allentown, on Thursday and is facing charges of attempted homicide, aggravated assault, simple assault and reckless endangerment, according to Morganelli.

Morganelli said Yang admitted to purchasing thallium and other chemicals online, but said he did so with the intent to harm himself if he performed poorly on school exams.