US criminology student Bryan Christopher Kohberger is in custody after being charged with first degree murder.
He is accused of killing Kaylee Goncalves, Maddie Mogen, Xana Kernodle and Ethan Chapin, who were stabbed to death in Moscow, Idaho in the early hours of 13 November in a case that left the small community where they lived desperate for answers.
Autopsies showed all four were likely asleep when they were attacked. Some had defensive wounds and each was stabbed multiple times.
So what do we know about the man held on suspicion of their deaths?
Kohberger is 28 and a PhD student in the Department of Criminal Justice and Criminology at Washington State University, a short drive across the state line from the University of Idaho.
He is also a teaching assistant for the university’s criminal justice and criminology programme, according to WSU’s online directory.
University police assisted Idaho law enforcement in executing search warrants at Kohberger’s home and office on campus.
A graduate of Northampton Community College in Pennsylvania in 2018, he holds an associate of arts degree in psychology.
‘Keen interest in crime’
DeSales University in Pennsylvania said he received a bachelor’s degree in 2020 and completed graduate studies in June 2022.
He was arrested early on Friday morning by Pennsylvania State Police at an address in the state’s Chestnuthill Township and is being held for extradition to Idaho on a warrant for first degree murder.
Sky News’ partner NBC News said Kohberger was most recently living in an apartment in Pullman, Washington, and appeared to have a keen interest in crime.
Fellow WSU criminal justice grad student Ben Roberts told the channel, Kohberger appeared confident and outgoing but also seemed like “he was always looking for a way to fit in”.
“It’s pretty out of left field,” Mr Roberts told The Associated Press. “I had honestly just pegged him as being super awkward.”
According to NBC, seven months ago, a person with the name Bryan Kohberger took part in a research project that required him to reach out directly to people who had been arrested.
At the time, the person identified himself as a “student investigator” at DeSales University and was using a school-issued email address.
“My name is Bryan, and I am inviting you to participate in a research project that seeks to understand how emotions and psychological traits influence decision-making when committing a crime,” Kohberger wrote in a post that appeared seven months ago on a Reddit community for former prisoners.
“In particular, this study seeks to understand the story behind your most recent criminal offence, with an emphasis on your thoughts and feelings throughout your experience.”
The stabbing deaths shook the small town of Moscow, Idaho, a farming community of about 25,000 people – including roughly 11,000 students – tucked in the rolling hills of the northern Idaho’s Palouse region.
An extradition hearing is scheduled for Tuesday.