A graduate student at Washington State University was arrested Friday in his home state of Pennsylvania in last month’s killings of four University of Idaho students in their off-campus home – a brutal attack that rattled a small college town

A criminal complaint charging Bryan Kohberger, 28, with four counts of murder in the first degree, as well as felony burglary, was filed Thursday. In relation to the four innocent students that were brutally murdered in their home just a few weeks ago.

Authorities narrowed their focus to Kohberger after tracing his ownership of a white Hyundai Elantra seen in the area of the killings, according to two law enforcement sources briefed on the investigation. Kohberger’s DNA has also been matched to genetic material recovered at the off-campus house where the students were stabbed to death, according to the sources.

Genetic genealogy helped investigators identify the suspect, a source with knowledge of the case said. DNA found in Idaho was taken through a public database to find potential matches for family members, the source said. Once potential family matches were found, subsequent investigative work by law enforcement led to the identification of Kohberger.

The suspect drove across country in the white car to his parents’ house, according to another law enforcement source. “Sometime right before Christmas we were zeroing in on him being in or going to Pennsylvania,”.

Kohberger completed his first semester as a PhD student in the school’s criminal justice program earlier this month.

An FBI surveillance team from the Philadelphia field office had been tracking him for four days in the area where he was arrested, according to the sources.

While he was being watched, investigators from the Moscow Police Department, the Idaho State Police homicide bureau, and the FBI worked with prosecutors to develop sufficient probable cause to obtain the warrant. Once the arrest warrant was issued, the Pennsylvania State Police and the FBI made the arrest.

Records show Kohberger was arraigned Friday morning in Pennsylvania, and he has a court hearing on extradition January 3. Thompson said the suspect is being held without bail, and he is being represented while in Pennsylvania by a public defender.

Because the suspect was arrested in Pennsylvania, he has the opportunity to waive extradition and return to Idaho voluntarily. If he chooses not to return voluntarily, Moscow police will initiate extradition proceedings through the governor’s office.