A graduate student from Saudi Arabia has admitted stabbing to death a professor in upstate New York.

Abdulsalam al-Zahrani (ab-DUHL’-sah-lam al-zah-RAH’-nee) pleaded guilty to first-degree manslaughter Friday. Broome County District Attorney Gerald Mollen says al-Zahrani had come to believe Binghamton University professor Richard Antoun was part of a plot against him and attacked him in his office in 2009.

Three months ago, the 48-year-old al-Zahrani had been sent to a psychiatric center where experts determined he was schizophrenic but mentally competent to stand trial.

The 77-year-old Antoun was an emeritus professor of anthropology and expert on Middle East cultures. Mollen says he’d helped al-Zahrani with his studies for years.

Under the plea deal, al-Zahrani is expected to be sentenced Sept. 9 to 15 years in prison and then face deportation.

Copyright 2011 The Associated Press.