New York University said on Wednesday it had been wrong in not immediately reporting to police accusations that a student set a sleeping classmate on fire over the summer, then recorded her as she put out the flames.

Jaime Castano was charged on Tuesday with assault and reckless endangerment; prosecutors said at his arraignment the university had not reported the case until mid-October. The incident occurred at an NYU dorm in August.

According to a criminal complaint, the girl fell asleep on Castano’s bed at about 11pm on 23 August. The next day, she had burns on her torso and clothes, and there were holes and burns on the comforter. Castano told her he had set fire to the comforter, according to the criminal complaint.

He took a cellphone video of the 19-year-old classmate with flames on her clothing while he sang, and she woke up and tried to put out the fire, prosecutors said.

NYU said on Wednesday the delay in reporting the incident to authorities stemmed from its practice of giving deference to a victim’s wishes to involve police. The woman did not want to go to police until recently, according to university spokesman John Beckman.

“In retrospect, at least when the facts became clear, this case clearly should have been reported to the police, notwithstanding the reluctance of the victim,” Beckman said.

Castano was expelled in September after the university pursued a disciplinary case. The 20-year-old was ordered held on $50,000 bond or $25,000 cash bail after Tuesday’s court appearance. His lawyer did not return a call seeking comment.

“The university, from the outset, took this case very seriously,” Beckman said in a statement, adding: “From the very beginning, the university spoke with the victim about involving the police.”

Beckman said the university was investigating the handling of the incident and “clarifying” the decision-making process “so that cases like this are reported to the police immediately in the future”.

New York University has more than 40,000 students, with tuition of about $60,000 per year.