A correction to an earlier version of this article has been appended to the end of the article.

A University of California-Santa Cruz computer science professor is on leave amid complaints of abusive racially and sexually charged remarks toward students including calling a Muslim graduate student a “terrorist” until he left the school citing “immense anguish” over his treatment.

Classmates have rallied in support of the students and criticized the administration’s handling of the matter and a complaint process they say protects faculty at the expense of students. They said the university took more than six months after the first student came forward to reach out to potential witnesses, and only did so after more than 500 students signed a petition demanding action.

In an Aug. 28 email to the engineering school dean obtained by this news organization, the Muslim student accused computer science and engineering professor Dimitris Achlioptas of repeatedly calling him a “terrorist” and “Ay-rab.”

The email also claimed the professor said the student’s beard made him look like a “most wanted” poster, belittled his intelligence and made sexually charged remarks about his genitalia and sexuality. The note identified a handful of students, professors and others who witnessed some of the alleged behavior.

A second graduate student corroborated the alleged “terrorist” remarks in a December complaint to administrators that detailed his own accusations of Achlioptas’ abusive, belittling and sexually charged remarks toward him.

The two students told this news organization that they did not want to be identified because they feared it would hurt their ability to find work. The Muslim student said he had to restart his studies at another university out of state.

Achlioptas referred questions about the accusations to his lawyer, Michael J. DeNiro.

“My client has confidence in the integrity of due process at UCSC, and is confident that he will be exonerated when the investigation that he violated the Faculty Code of Conduct ends,” DeNiro said. Achlioptas, he added, would not comment on the specific allegations because those involved “are bound to keep the matters being investigated in confidence.”

In a joint statement Wednesday, Marlene Tromp, campus provost and executive vice chancellor, and Alexander Wolf, dean of the university’s engineering school, said the university is investigating allegations that “are serious and troubling,” and the professor is on leave.

“When UC Santa Cruz first became aware of such allegations, we alerted the appropriate campus offices for follow-up and investigation,” the statement said. “We understand our community’s alarm that our silence on this matter signals tolerance. This is simply untrue.”

They added that “the safety and well-being of our students is our highest priority, and we treat allegations of misconduct by anyone — faculty, staff, or students — with seriousness and care.” But citing privacy and due-process rights, they said “there is also very little we can say publicly.”

According to profiles posted online by UC, Achlioptas was born in Canada, earned a doctorate from the University of Toronto in 1999 and did graduate work in Greece. He joined UCSC in 2006 after working for Microsoft Research in Redmond to study how algorithms can be applied to cellular biology. His research specializes in exploring the use of random structures both as aids and as obstacles to efficient computation, and he has received a National Science Foundation career award. Most of the anonymous student comments about Achlioptas on the website ratemyprofessors.com were positive, even calling him “inspirational,” although some expressed concerns.

The Muslim student followed up his Aug. 28 email with a Jan. 17 note to the chancellor’s office complaining that “not a single investigator has met with any students,” even though his original email had identified students and professors who had witnessed the professor’s alleged abuse.

After students began sharing concerns about the matter on Facebook and Reddit, Wolf posted a note to engineering school students Feb. 28 acknowledging the “troubling posts on social media” and assuring students the concerns were being investigated. He said “harassment, bullying, racism — and other forms of abusive conduct — have no place in our school or the university,” but urged students to avoid “speculation” on social media to “protect the privacy of everyone involved.”

Tromp and Wolf did not comment on the students’ specific criticisms of the university’s response to the Achlioptas complaints.

Engineering school student club leaders in a statement to the administration said the university “has repeatedly failed in its duty to protect students” and that “reporting structures must be changed to prevent future failures.”

“We agree that there are specifics on the case that the university is unable to publicly disclose,” Simran Chawla, president of the engineering school’s Society of Women Engineers, told this news organization. “We do not agree that this prevents the university in any way from better protecting students and acting when complaints are raised, rather than only when there is a petition that gains traction.”