Police said 20-year-old Nicholas Barnes, a third-year student, had been dead for some time. The last time he used his keycard to enter the International House, where he lived, was February 7.
In an email to students, vice president for campus life and student services Karen Warren Coleman said there was no evidence of foul play, and that the university is investigating the circumstances of Barnes' death.
"I don't understand how the people that live next door, and the people who were responsible for his well-being could have not seen that he has been gone for a week," said International House resident Jordan Ginsburg.
The Cook County medical examiner's office said an autopsy conducted Sunday was inconclusive and toxicology reports are pending, adding that Barnes' death is not believed to be a suicide.
Barnes, who grew up in Pittsburgh, was majoring in Germanic Studies and studied abroad in Austria.
"Nick will be painfully missed," Dean of Students Susan Art wrote in an email to students. "He was an excellent student, admired by faculty and peers alike."
The university is holding a memorial on campus and Barnes' family is planning the funeral in Pennsylvania.