While authorities found no evidence of foul play, the Cook County, Ill., medical examiner's office couldn't immediately say whether Harsha Maddula's death was accidental.
The cause was listed as "undetermined," pending a battery of toxicology tests.
"We need to find the answers," said Sushma Maddula, a cousin speaking for the family. "That is what is truly upsetting: We don't have answers to our questions."
At a vigil last night outside the university library, about 500 people gave Maddula's family what they could: condolences and a celebration of the student's life. Five religious groups offered prayers.
"Harsha had an insight into what brings us all together," said Linzy Wagner, president of the Public Affairs Residential College, where Maddula was the philanthropy chair. "We should all strive to do what he did."
Many came not to mourn a friend but to reflect on a tragedy.
"Harsha's story could have been any of ours," said Victor Shao, student government president.
Ending a massive, six-day search, the student's body was found Thursday evening between two boats at Wilmette Harbor, less than two miles north of his dorm.
Maddula was last seen at 12:30 a.m. Sept. 22, leaving an off-campus party in Evanston. When they recovered his body, police found his wallet and cellphone in his pants pockets.
University officials earlier this week said it wasn't clear whether Maddula left the party alone or with a group, or who he was last with. The student's family said he had been recently diagnosed with diabetes, sparking speculation that the disease may have contributed somehow to the disappearance.
But a preliminary test of fluids in Maddula's eyes indicated that his blood-glucose level was normal.
"At the time of his death he did not have high glucose," a medical examiner's office spokeswoman said. Additional tests are planned to confirm the finding.
Friday, Sushma Maddula and about two dozen relatives gathered at Northwestern campus and urged students who attended the Evanston party to come forward with any new information.
"Something happened at this party, we know that," Sushma Maddula said. "We really need students to speak up . . . We appreciate all the efforts, but we do need more help."
Harsha Maddula, by all accounts, was an accomplished student who was focused on one thing: his education.
"He was always into the books. That's what he was about," said Brandon Mohan, 14, who lives next door to Maddula's family home in Garden City Park.
Richard Faccio, principal of New Hyde Park Memorial High School, where Maddula graduated in 2011, lamented the loss of the "standout" student who was a member of the Science Olympiad and Future Business Leaders of America..
"He was a leader among kids," Faccio said.
With Joseph Mallia and David Uberti