(NewsNation) — Police on Friday arrested 28-year-old Bryan Christopher Kohberger in connection with the November deaths of four University of Idaho students who were stabbed to death in a rental house near campus.

The suspect was arrested on a warrant early Friday morning in Monroe County, Pennsylvania. A criminal complaint filed in Idaho charges Kohberger with four counts of first-degree murder and one count of felony burglary, Latah County, Idaho Prosecutor Bill Thompson said.

Sources confirmed to NewsNation that Kohberger was on suicide watch in the Pennsylvania jail where he was being held and had asked officers at one point whether anyone else was arrested. Sources said Kohberger has had a “quiet, blank stare” throughout the process.

Kohberger is scheduled for an extradition hearing Tuesday, Monroe County court records show, but Jason Allen LaBar, Monroe County’s chief public defender, said he plans to waive it to expedite his transport to Idaho.

“Mr. Kohberger is eager to be exonerated of these charges and looks forward to resolving these matters as promptly as possible,” LaBar said.

A friend of Kohberger told NewsNation affiliate WBRE he was “in complete shock” when he learned he was arrested.

“I used to go on night runs with him because I didn’t want to run by myself, so I would text and be like, ‘hey, do you want to go for a run?’ We’d go for six or seven-mile runs at night,” Schyler Jacobson said. “I’m still kind of shaking knowing about that. It’s just unreal to think somebody could actually do that to somebody. It’s absolutely mind-boggling.”

Kohberger’s arrest is linked to the Nov. 13 stabbing deaths of the four students — 21-year-old Kaylee Goncalves; Madison Mogen, 21; Xana Kernodle, 20 and 20-year-old Ethan Chapin. During the weeks-long investigation into their deaths, police chased thousands of tips after the crime drew nationwide attention.

The case broke open after law enforcement asked the public for help finding a white sedan seen near the home around the time of the killings.

Officers have since discovered the Hyundai Elantra they were looking for, but have yet to locate the weapon used during the stabbings, Moscow Police Chief James Fry said.

Officers did not say whether they specifically received tips about Kohberger.

The 28-year-old was attending Washington State University as a Ph.D. student in the Department of Criminal Justice and Criminology at the time of his arrest, investigators confirmed Friday. The school is just miles across state lines from Moscow, Idaho.

The university in a statement said Kohberger completed his first semester there “earlier this month.”

“On behalf of the WSU Pullman community, I want to offer my sincere thanks to all of the law enforcement agencies that have been working tirelessly to solve this crime,” said Elizabeth Chilton, chancellor of the WSU Pullman campus and WSU provost. “This horrific act has shaken everyone in the Palouse region.”

A minor traffic citation he received in August out of Latah County, Idaho suggests that Kohberger had previously been in the area where Moscow is located. There is no known connection between that violation and the November deaths.

Kohberger received a bachelor’s degree in 2020 and completed a Master of Arts in Criminal Justice in June from DeSales University, the school confirmed to NewsNation.

“As a Catholic, Salesian community, we are devastated by this senseless tragedy,” the university said in a statement. “Our thoughts and prayers are with the victims’ families during this difficult time.”

A DeSales student with the same name was part of a research project that involved surveying people about crimes they had committed.

A Reddit post from this spring by someone who identified themselves as Kohberger and listed a university email with the initials “BK” sought participants for the anonymous survey. It is unclear if Kohberger made the post.

The survey — which was removed from the university website Friday — included questions about respondents’ feelings and emotions while committing an offense, how they identified their target, what they did when they left and additional questions about their mental state.

The Reddit post was also removed Friday and the poster’s account has been suspended.

This is a developing report. Refresh for updates.

The Associated Press contributed to this report.