ITHACA, N.Y. — Cornell University will prohibit fraternities from holding parties and social events for the remainder of the academic year, President Michael I. Kotlikoff announced Tuesday, as the university faces renewed scrutiny over its response to a former student’s allegations of sexual assault at a fraternity house. The university also plans to bring New York State Police criminal investigators into campus sexual-assault investigations when survivors pursue criminal charges. Cornell said it will expand staffing in its civil rights office, strengthen bystander training and seek faculty experts to help reform its Presidential Task Force on Sexual Assault. In a letter to the campus community, Kotlikoff apologized for the harm alleged by the former student, identified in a civil lawsuit as Jane Doe. “It is clear that women on our campus continue to question whether they are safe,” he wrote, promising “meaningful action.” Doe’s lawsuit, filed nearly a month before the announcement, alleges that members of the Chi Phi fraternity gave her ketamine and sexually assaulted her during a party in October 2024. The allegations have not been established in court. The lawsuit also describes fraternity members discussing Doe and the party in a Snapchat group chat, prompting widespread anger. The announcement came after students organized campus protests last week and amid a planned Tuesday rally near the university. Cornell sophomore John Hartnett, a protest organizer, called the changes a “half measure,” saying a temporary ban would not resolve what he described as systemic problems. Associate professor Julia Chang said trust on campus remains damaged and argued that the timing of the changes reflected pressure from student activism. The faculty senate was scheduled to consider a no-confidence vote in the administration on Wednesday, a sign of deep frustration over the university’s handling of the case. About one-third of Cornell students participate in fraternities or sororities, making the event moratorium a significant change to campus social life. Kotlikoff said the university’s relationship with Greek life has contributed to a harmful culture that requires correction, while noting that the problems are not unique to Cornell. The district attorney did not prosecute the case in 2024. Cornell’s Title IX office investigated in 2025, and a university panel later moved to expel or suspend some of the men, according to the university’s account; others faced sanctions that included writing essays. The Chi Phi chapter was barred and closed in 2024. Kotlikoff’s letter did not explain why the new measures were being announced two years after university officials learned of the allegations. The university said state investigators would be independent of Cornell and able to take on cases when survivors seek criminal charges.