Bryan Kohberger, a graduate student at Washington State University, has been arrested in connection to the November murders of four University of Idaho students.
DNA technology led to Kohberger being identified as a suspect, and he was tracked to Pennsylvania through his car.
The FBI had been surveilling the house where Kohberger was arrested before moving in to arrest him.
The motive for the murders and details leading to Kohberger's arrest have not been disclosed.
Kohberger is facing four counts of first-degree murder and burglary and is being held without bond in Pennsylvania.
He is scheduled to return to court on Tuesday for the extradition process.
The murder weapon has not been found, and two roommates of the victims, who are not suspects, survived the attack.
Kohberger received his undergraduate degree from DeSales University in 2020 and completed graduate studies there in 2022. He is a Ph.D. student in the department of criminal justice and criminology at Washington State University.