Officials at the local medical examiner’s office said they had performed an autopsy, but did not have final results and would not release information on the cause of death until they did. University of Iowa police said their investigation was continuing, but that Gerald Belz’s death was believed to be related to the weather.

A pre-med student, he had been in contact with his girlfriend, Leeanne Mehring-Cruz, through text messages and Snapchat video in the hours before he died, but had dropped off social media around 1 a.m.

Ms. Mehring-Cruz, who lives in Cedar Rapids, said she had been seeing Gerald Belz for two years. She described him as sweet and brilliant, someone who only showed his soft side to his closest family and friends. One of the last things he wrote that last night, she said in an interview conducted over Twitter, was that he loved how she was always there for him through everything.

“I wish I could have protected him then,” she said.

Ms. Mehring-Cruz said she is hoping the police will quickly find out where he was going and what happened to him. “I have no clue what he was doing,” she said. “The last messages we sent were I love you’s and good night’s.”

Michael Belz said Gerald, the older of his two sons, was careful and compassionate, studious and avid rugby player who wanted to become a doctor. He was already ahead in his college studies because he had completed Advanced Placement classes in high school.

He played football in high school, but then turned to rugby. “He loved it, much to the chagrin of his mother, who wanted to protect him and keep him safe,” the father said. “He had a great time with it.”

The Belzes last saw their son on Sunday evening, when he was visiting home. Snow had started to fall, and Michael Belz urged him to head back to campus before things got too slippery.

So Gerald gathered up his things, said his goodbyes and drove back to his dorm. Around 10 p.m., he called his mother to give her the customary assurance: He had arrived safely.