At Washington State, Mr. Kohberger was continuing with his studies, his classmates said. B.K. Norton, who was in the same graduate program as Mr. Kohberger, said his quiet, intense demeanor had made some classmates uncomfortable.
Another student said Mr. Kohberger seemed interested in the thought processes of criminals while they committed crimes and less interested in the social factors that might lead people to do so, saying that he believed some people were just bound to break the law. The fellow student, who spoke on the condition of anonymity because he feared that speaking publicly could jeopardize his safety, described Mr. Kohberger as the black sheep of the class, often taking contrarian viewpoints and sometimes getting into arguments with his peers, particularly women.
The classmate recalled one instance in which Mr. Kohberger began explaining a somewhat elementary criminology concept to a fellow doctoral student, who then accused him of “mansplaining.” A heated back-and-forth ensued and the doctoral student eventually stormed out of the classroom, leaving behind her laptop and coffee, he said.
Mr. Kohberger was also a teaching assistant in a criminal law class during the fall semester, said Hayden Stinchfield, 20, one of the students in that class. He said that Mr. Kohberger often cast his eyes down while addressing the students, giving the impression that he was uncomfortable.
Students said Mr. Kohberger had a strong grasp of the subject matter but was a harsh grader, giving extensive critiques of assignments and then defending the lower marks when students complained as a group. Later in the fall, roughly around the time of the killings, Mr. Stinchfield said Mr. Kohberger seemed to start giving better grades, and the assignments that once had his feedback scrawled across every paragraph began coming back clean.
“At a certain point he stopped leaving all the notes,” he said.
At the time, a growing team of investigators from local and state agencies, as well as more than 60 agents from the F.B.I., had descended on Moscow. Forensics investigators combed the house for physical evidence, including D.N.A., and searched fruitlessly for a murder weapon.
Officials pleaded for tips and videos, while thousands of internet sleuths around the country suggested an array of people as the likely culprit: a former boyfriend of one of the victims, a man who was with two of the victims when they got a meal from a food truck, two roommates who were in the home when the killings occurred but apparently slept through them.
