(AP) — An arrest has been made in the November fatal stabbings of four University of Idaho students, a case that shocked the small college town of Moscow and seemed to perplex investigators for weeks.

Here is a look at what is known about the killings, and the latest developments.

WHAT WAS THE BREAK IN THE CASE?

Bryan Christopher Kohberger, 28, was arrested early Friday morning by the Pennsylvania State Police at a home in Chestnuthill Township, authorities said. He is being held for extradition to Idaho on a warrant for first-degree murder, according to arrest paperwork filed in Monroe County Court. Latah County Prosecutor Bill Thompson said investigators believe Kohberger broke into the students’ home “with the intent to commit murder.” An extradition hearing is scheduled for Tuesday and authorities, citing Idaho law, declined to discuss details, including what led them to the suspect or a possible motive.

WHAT IS KNOWN ABOUT THE SUSPECT?

Kohberger is a Ph.D student in the Department of Criminal Justice and Criminology at Washington State University, which is about nine miles (14.5 kilometers) west of the University of Idaho. He graduated from Northampton Community College in Pennsylvania with an associate of arts degree in psychology in 2018. DeSales University in Pennsylvania said that he received a bachelor’s degree in 2020 and completed graduate studies in June 2022.

WHO WERE THE VICTIMS?

All four were friends and members of the university’s Greek system. Xana Kernodle, 20, was a junior studying marketing. She was from Post Falls, Idaho, and joined the Pi Beta Phi sorority on campus. She lived at the rental home with the other two women who were stabbed, and she was dating Ethan Chapin, who was visiting the night of the killings.

Chapin, also 20, was from Conway, Washington, and was a triplet. His brother and sister also attend UI, and both Chapin and his brother were members of the Sigma Chi fraternity.

Kaylee Goncalves and Madison Mogen were both 21 and friends who grew up together in northern Idaho. Mogen worked with Kernodle at a Greek restaurant in Moscow. She was also a member of Pi Beta Phi.

Goncalves was a senior majoring in general studies, a member of the Alpha Phi sorority and was planning a trip to Europe next year.

WHAT HAPPENED THE NIGHT AND MORNING OF THE ATTACK?

Goncalves and Mogen went to a bar, stopped at a food truck and then caught a ride home around 2 a.m. Nov. 13, according to a police timeline of the evening.

Chapin and Kernodle were at the Sigma Chi house just a short walk away and returned to Kernodle’s house around 1:45 a.m., police said.

Two other roommates who live in the home were also out that evening, but returned home by 1 a.m., police said. They didn’t wake up until later that morning.

After they woke up, they called friends to come to the house because they believed one of the victims found on the second floor had passed out and wasn’t waking up. At 11:58 a.m., someone inside the home called 911, using a roommate’s cel phone. Multiple people talked with the dispatcher before police arrived.

Police found two of the victims on the second floor of the three-story home, and two on the third floor. A dog was also at the home, unharmed.

Autopsies showed the four were all likely asleep when they were attacked; some had defensive wounds and each was stabbed multiple times. There was no sign of sexual assault, police said.

WERE THE VICTIMS TARGETED?

It’s unclear whether the killer or killers knew the victims. Police and the county prosecutor’s office have released confusing — and at times contradictory — statements.

Investigators say nothing appears to have been stolen from the home.

WHAT WAS THE RESPONSE FROM POLICE AND THE COMMUNITY?

Police initially said there was no threat to the community of 25,000 nestled in the rolling Palouse hills, then later walked back that statement. Many residents have been fearful since the slayings.

The University of Idaho has allowed students to switch to fully remote learning.

The university has also hired an additional security firm to help with campus safety. Students can request escorts while on campus.