Accused killer Bryan Kohberger went through a dramatic change around the time of the deaths of four University of Idaho students, according to a former student of Kohberger’s. Hayden Stinchfield, who attends Washington State University in Pullman, Washington, said Kohberger, a Ph.D. student in criminology at the college, was a teaching assistant for one of his courses. Kohberger, 28, has been charged with four counts of first-degree murder and felony burglary in the Nov. 13, deaths of Kaylee Goncalves, 21, of Rathdrum, Idaho, Madison Mogen, 21, of Coeur d’Alene, Idaho; Xana Kernodle, 20, of Post Falls, Idaho; and Ethan Chapin, 20, of Mount Vernon, Washington, according to CNN. Stinchfield said he was stunned to learn Kohberger had been arrested. “This person who had been, you know, kind of grading my papers, was allegedly this like horrible murderer,” he said, according to CNN. In a video showing his full comments, Stinchfield said the change that took place around the time of the killings was striking. “Definitely around then, he started grading everybody just 100s. Pretty much if you turned something in, you were getting high marks,” he said. “He stopped leaving notes. It was just, he seemed preoccupied,” the student added. He said that after the murders, Kohberger changed physically as well. “The couple times that he did come after, or around that time period, he had a little more facial hair, stubble, less well-kept than he was and he was a little quieter.” “The previous mental preoccupation that we had been noticing, where it was like he didn’t really want to be there, that was at an all-time high,” Stinchfield said. “He just didn’t look like he was doing great.” Stinchfield said the class looked upon Stinchfield called Kohberger as “a little weird and a bad grader.” “We were all annoyed by him,” he said. “He’d be grading you on what he ended up calling a ‘higher standard,'” Stinchfield said.”But what it really felt like to us was he was grading us like he would have graded himself as a Ph.D. student.” Stinchfield said during one class students in the course were able to argue their grades because their professor gave them the chance to hone their persuasive skills. “He brought in Bryan, and he was like, ‘alright, go at him,'” Stinchfield said. “And he had Bryan stand up… And a few people were on his side because they wanted to keep their high grades… but for the most part, it was like half of a 150-person class just asking him all these really critical questions.” He said Kohberger defended himself in a situation Stinchfield called “conflict.” Joey Famularo, another WSU student who had Kohberger for a criminology class said the suspected killer “always seemed a little bit on edge,” according to The Spokesman-Review. ”We just assumed he was kind of shy,” Famularo said. ABC. This article appeared originally on The Western Journal.