VESTAL, N.Y. — In this small upstate college town, there were many who tried to comprehend how a popular 77-year-old professor who championed antiwar philosophies would have come to such a violent end: stabbed to death in his office on Friday, by, the police said, a graduate student whom he knew.
Then there were those who said they had noticed signs of erratic behavior by the suspect, a graduate student at Binghamton University, who, they said, was becoming increasingly fearful — so much so that his roommate said he had warned university officials of his concerns.
The suspect, Abdulsalam S. al-Zahrani, 46, remained held without bail on Sunday, charged with second-degree murder in the death of the professor, Richard T. Antoun.
The two knew each other through Binghamton's graduate program, where the professor served on the dissertation committee for Mr. Zahrani, who is from Saudi Arabia.
On Sunday, Mr. Zahrani's roommates — who had lived with him for about three weeks in a three-bedroom apartment in downtown Binghamton — recounted how the suspect, who spoke of financial problems, often mentioned death and said he was being persecuted because he was Muslim.
"I said he was acting oddly, like a terrorist," said one of the roommates, Souleymane Sakho, a graduate student from Senegal. "When I informed them, it was for them to understand that the guy was violent or he may be violent."
Mr. Sakho said that he told his academic adviser who is overseeing his dissertation about Mr. Zahrani, and that the adviser referred him to the school's counseling center. Mr. Sakho said that the head of the counseling center told him to avoid interaction with Mr. Zahrani and said he should look to move out of the apartment.
A spokesman for Binghamton University declined to comment on what university officials may have been told by Mr. Sakho about Mr. Zahrani's behavior, citing a continuing investigation by the district attorney of Broome County.
The district attorney, Gerald F. Mollen, declined to discuss many details of the case in a telephone interview, only saying that an autopsy performed on Dr. Antoun showed that he died of multiple stab wounds.
"There are no new details and we are not going to be providing a debriefing every minute for every development," Mr. Mollen said.
About 10 days ago, the police were called to the three-bedroom apartment, according to Mr. Sakho. He said he was sick of Mr. Zahrani's constantly asking him if he was afraid of death and told him to stop. Later that night, Mr. Sakho said he told his other roommate, Luis Pena, also a graduate student, that he "had enough of the situation." Hearing them, Mr. Zahrani came out of his bedroom and accused Mr. Sakho of threatening him, Mr. Sakho said.
"I'm not the kind of person to make threats because I am a peaceful person," said Mr. Sakho, recalling the conversation. "I just want you to stop what you are doing."
Mr. Zahrani then called the Binghamton police, who arrived at the apartment several minutes later, Mr. Sakho said.
"I came out and wanted to explain what Zahrani was doing and they told me to go back to my room," Mr. Sakho said.
Dr. Antoun, an anthropology professor who focused on Islamic and Middle Eastern studies, retired in 1999, becoming a professor emeritus at Binghamton, which is considered a jewel of the New York State university system. He still advised several students studying for master's and doctoral degrees and came into the office every day, according to Nina M. Versaggi, an anthropology professor who has an office a few doors down from Dr. Antoun's.
Dr. Antoun held season tickets to the Binghamton men's basketball team and had plans to attend Friday night's game. "I had just talked to him a couple of hours earlier; we ran into each other in the mail room," said Dr. Versaggi. "We both have tickets to the basketball game and he said he planned to go to the game. Even though the team is rebuilding, he said they were showing some promise. He was just happy as usual, just a good-humored man."
Dr. Versaggi declined to discuss many of the specifics of the events on Friday. She said that although her office is a few doors down from Dr. Antoun's, she first learned of the stabbing when she received a phone call and was instructed to go into "lockdown mode."
"He was a scholar in the true meaning of the word," said Dr. Versaggi. "A very peaceful and gentle man, and he was a professor who spent his entire career working towards fairness and justice. The only firm stance he has ever taken on any issue is that he was antiwar and a peace activist. The last time I remember him protesting was against the Iraq war."
Mr. Sakho and Mr. Pena said that Mr. Zahrani told them he had lived in Montana before returning to Binghamton to finish his doctoral thesis. They said he told them that the university had recently denied his request for financial support; they added that he never talked about Dr. Antoun.
Mr. Sakho said the last time he saw Mr. Zahrani was around 1 a.m. on Friday, when Mr. Zahrani woke him up and once again asked him if he was afraid of dying. Mr. Sakho said he did not respond to Mr. Zahrani and went back to sleep.