"He pretty much never talked at all," said Joseph Aust, who shared a bedroom with him in a six-person dorm suite in Harper Hall. "I tried to make conversation with him earlier in the year. He gave one-word answers."
"He pretty much never looked me in the eye," Aust said.
In recent weeks his routine had changed. His roommates say he went to the campus gym at night, lifting weights to bulk up. He went for a haircut -- surprising them by coming back to the room with a military-style buzz cut.
Aust and another roommate, Karan Grewal, say they were aware that Cho had pursued women on campus. They said he also seemed to have an imaginary girlfriend, a supermodel named "Jelly."
Students say he seemed as quiet as ever in the days before Monday's rampage.
Trey Perkins, a student who saw Cho during the shooting spree, said it was unreal, "being that close to a monster."