STANFORD, Calif. (AP) — A Stanford student’s death at a fraternity house last month has been ruled the result of a fentanyl overdose, the Santa Clara County Medical Examiner’s Office announced Wednesday.

The medical examiner made the ruling in the Jan. 17th death of Eitan Weiner, who body was found at the Theta Delta Chi fraternity house.

“After a thorough investigation, the Santa Clara County Medical Examiner-Coroner’s Office has officially determined that Eitan’s death was ruled an accident due to fentanyl toxicity,” the Santa County Sheriff’s Office said in a release. “This is still an ongoing investigation and we are working closely with officials at Stanford to ensure the public’s safety.”

Fire officials told sheriff’s deputies they were called to the house, found an unresponsive man and pronounced him dead at 10:21 a.m, the San Francisco Chronicle reported.

Students, teachers and staff were notified of the death in a letter from Susie Brubaker-Cole, the university’s vice provost. She said the student was an undergraduate but the school did not release his identity.

“This is very difficult news for any family to bear. Our university community grieves with them,” Brubaker-Cole said.