BOULDER, Colo. - A University of Colorado student pleaded not guilty Wednesday to making comments that classmates deemed sympathetic toward the gunman blamed for killing 32 students and himself at Virginia Tech, authorities said.

During a class discussion Tuesday of Monday's massacre at Virginia Tech, Max Karson "made comments about understanding how someone could kill 32 people," university police Cmdr. Brad Wiesley said.

Several witnesses told investigators Karson, who turns 22 on Thursday, said he was "angry about all kinds of things from the fluorescent light bulbs to the unpainted walls, and it made him angry enough to kill people," according to a police report. Witnesses "said they were afraid of him and afraid to come to class with him," Wiesley said.

Karson, of Denver, was arrested Tuesday on a misdemeanor charge of interfering with staff, faculty or students of an education institution.

His father, Michael Karson, told the Camera newspaper that the comments may have been misinterpreted and questioned whether his son's free speech rights had been violated.

"I would have hoped that state officials would know their First Amendment better than they seem to," he said.

University spokesman Bronson Hilliard said privacy laws prevented him from releasing personal information about students.

At Oregon's Lewis & Clark College, another student was detained by campus police Wednesday shortly before a vigil for the Virginia Tech victims when he was spotted wearing an ammunition belt. Portland police later determined that it was "a fashion accessory" made of spent ammunition, and said the man did not have a weapon. The belt was confiscated.