Los Angeles ? A UCLA professor said he told a university administrator 10 months ago of his concerns about the mental health of a student now accused of stabbing a fellow student in the throat in a chemistry lab.

UCLA history professor Stephen Frank said he met the suspect — 20-year-old Damon Thompson — in his Western civilization class late last year.

Frank told the Los Angeles Times he became worried when Thompson sent several e-mails complaining that classmates sitting near him had made offensive comments to him while he was taking a written exam. In one e-mail, Thompson also accused Frank of taunting him.

Frank said he was present during the entire exam and saw nothing to support Thompson’s complaints. Several teaching assistants also said they saw nothing unusual, Frank said.

Detectives have been trying to discover a motive for the Thursday attack, in which stunned students watched in horror as blood gushed from the 20-year-old woman’s neck. Authorities have said Thompson and the woman, who police haven’t identified, were not romantically involved.