Bryan Christopher Kohberger’s demeanor changed suddenly after the murders of four University of Idaho students in November, according to a classmate of the accused killer.

“I did notice he was showing up to class a little late sometimes, he always had a coffee in hand, he always seemed to be just perpetually exhausted,” Washington State University graduate student Benjamin Roberts told News Nation.

Roberts added: “Bryan seemed like he was on the knife’s edge between exhaustion and worn out and at the time it was extremely difficult to tell which was which.”

The comments come after authorities on Friday arrested the 28-year-old Kohberger on four counts of first-degree murder and one count of felony burglary in connection with the deaths of Kaylee Goncalves, Maddie Mogen, Xana Kernodle and Ethan Chapin, who were found stabbed to death inside an off-campus residence on November 13 in Moscow, Idaho.

Kohberger is a first-year Ph.D. student at Washington State University in Pullman, Washington, just a short drive from Moscow. He was reportedly studying criminology.

In the interview with News Nation, Roberts said that after the slayings, Kohberger seemed to become more talkative, telling the outlet that Kohberger “did seem to get a little chattier going into the later parts of the term.”

Roberts also said that Kohberger seemed as if he wanted people to know that he was very smart.

“He had to make absolutely sure you knew he was smart, he had this intellectual capacity,” Roberts told News Nation.

Authorities took Kohberger into custody at his parents’ home in Albrightsville, Pennsylvania, where is believed to have traveled for the holidays.

A lawyer for Kohberger has said that his client is “eager to be exonerated” and will waive extradition to Idaho, CNN reports.

Kohberger is scheduled to appear in court on Tuesday.

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[Featured image: Bryan Kohberger/Monroe County Correctional Facility]