SYRACUSE - A former college professor accused of launching a campaign of threatening e-mails and phone messages after losing his job last year was tracked down with the help of former colleagues and arrested, authorities said.

Xiang Li, a 42-year-old Chinese national who worked at Morrisville State College during the 2005-2006 school year, is being held on federal charges he made interstate threats to injure or kill another person.

David Rogers, the school's dean, said Li was enraged when told his temporary contract as a professor of computer information technology was not going to be renewed because students found him abusive and sometimes belligerent.

“This isn't over yet. People who hurt me, I hurt them. And this isn't over,” Rogers recalled Li saying.

Li was fired and barred from the campus after the confrontation with Rogers in May 2006. He then moved out of New York and began threatening Rogers and others at the school in September, according to a federal criminal complaint.

Among the messages were threats to castrate a former colleague and to kill the child of another and the taunt, “Do you think they can protect you from a man who wants to die and wants to kill you?”

Campus and local police bolstered security as Morrisville State computer professors teamed up with authorities to track the e-mails.

FBI Special Agent Mark Shelhamer said the trail led to a Yahoo account and investigators got warrants to match the account against the threatening e-mails, which were sent from Indianapolis between late September to mid-March.

Li was arrested by U.S. marshals last month at an airport in Pittsburgh, where a federal magistrate said Li is in the U.S. illegally with an expired visa and he should undergo a mental evaluation in New York.

He was sent to Syracuse on Thursday. On Friday, U.S. Magistrate Gustave DiBianco ordered Li to remain in federal custody while his case is presented to a grand jury.