A former Lehigh University student already charged with lacing his roommate's food and beverages with toxin is being investigated for possibly poisoning another person at the school.

Yukai Yang, a student from China who was studying chemistry at the Bethlehem, Pennsylvania school, was arrested on Dec. 20 after prosecutors said he allegedly poisoned his roommate, Juwan Royal, 22, by adding small amounts of thallium and possibly other chemicals to Royal's food, drinks and mouthwash.

Northampton County District Attorney John Morganelli said Thursday that his office is investigating a potential second student being poisoned by Yang, The Morning Call reported.

Yukai Yang is accused of trying to poison his roommate to death and vandalizing the victim's possessions with racist graffiti. Northampton County Department of Corrections

“That is in the early stages of investigation," Morganelli told the paper, adding that the new allegations came to light after they announced the previous charges against Yang.

Morganelli did not provide any further details and has not yet returned NBC News' request for comment. Prosecutors are also asking for Yang to be held without bail, saying he is a "legitimate flight risk" after they foiled his plan to flee the United States over Christmas.

Morganelli told the outlet that Yang allegedly planned to waive his right for a deportation hearing after he was released on bail last week.

“Mr. Yang thought that because he is a foreign national, now here illegally in that his student visa has been revoked, that he could post bail, waive his right to a deportation hearing and abscond,” Morganelli said. “That will not happen.”

Yang is currently back in county jail. A hearing for prosecutors' bail request has not yet been scheduled.

Authorities discovered his roommate, who is black, had allegedly been poisoned while investigating a separate incident in which Yang was accused of writing a racial epithet on Royal's desk

Yang admitted that he purchased various chemicals with the intent of harming himself if he did poorly on his exams. He said he had mixed the toxins in foods and drinks he kept in the refrigerator he shared with Royal.

He was charged with attempted homicide, aggravated assault, simple assault and reckless endangerment for the poisoning incident. Yang was also charged with ethnic intimidation, institutional vandalism and criminal mischief for allegedly writing a racial slur on Royal’s belongings.