CHESTNUTHILL TWP., Pa. -- A suspect in the murders of four University of Idaho students was arrested Friday in Pennsylvania's Pocono Mountains region.
Bryan Christopher Kohberger, 28, appeared before a judge in Pennsylvania earlier Friday. Kohberger now has the option to either waive extradition and return voluntarily to Idaho, or Idaho will initiate extradition proceedings through their governor's office.
He is facing four counts of first degree murder as well as a felony burglary charge in Idaho.
At a briefing Friday afternoon, Latah County Prosecutor Bill Thompson confirmed Kohberger is a graduate student at Washington State University and has an apartment in Pullman, Washington -- just over the Idaho border, about 15 minutes from the crime scene.
Police did not disclose a motive or what led them to their suspect. The probable cause affidavit, which details the reasons for Kohberger's arrest, is sealed and cannot be released until he returns to Idaho, Latah County Prosecutor Bill Thompson said.
Authorities are still working to investigate how Kohberger was connected to the victims.
WATCH | Idaho authorities update public after college murder suspect's arrest
The family of victim Kaylee Goncalves tells ABC News they don't know the suspect, but they are seeing connections between the two that they aren't ready to discuss yet. The family said they are "happy, relieved and thankful" that there's been an arrest.
Sources say that authorities knew who they were looking for and had tracked Kohberger to Chestnuthill Township, Pa.
According to a criminal complaint, Pennsylvania State Police were assisting the Moscow (Idaho) Police Department, Idaho State Police and the FBI to take Kohberger into custody on a first-degree murder warrant.
WATCH | Who is Bryan Kohberger? What we know about the suspect
The warrant was issued through the Moscow Police Department and the Latah County Prosecutor's Office.
A SWAT team entered the location Kohberger was staying in and took him into custody, sources say.
Moscow's deputy city supervisor, Tyler Palmer, called the arrest a "tremendous sigh of relief for a community holding its breath for more than six weeks."
At Friday's news conference, authorities urged anyone familiar with Kohberger to contact them.
"You all now know the name of the person who's been charged with these offenses," Thompson said. Please get that information out there. Please ask the public, anyone who knows about this individual to come forward. Call the tip line. Report anything you know about him to help the investigators and eventually our office and the court system understand fully everything there is to know, about not only the individual, but what happened and why."
Anyone with information can call the dedicated tip line at 208-883-7180 or email firstname.lastname@example.org.
The police department's announcement of the news conference comes a day after police said they have received about 20,000 tips through more than 9,025 emails, 4,575 phone calls, and 6,050 digital media submissions, while having conducted over 300 interviews in the case of the four students slain in an off-campus home.
The students, Goncalves, 21; Madison Mogen, 21; Xana Kernodle, 20; and Kernodle's boyfriend, Ethan Chapin, 20; were likely asleep when they were each stabbed multiple times in the early hours of November 13, authorities have said.
Some of the victims had defensive wounds, a coroner has said. There was no sign of sexual assault, police said
The killings happened in the girls' off-campus house. Property managers there said Friday they had been told there was a major development in the case and the planned remediation process will need to be halted temporarily. The cleaning company had just set up and had not started cleaning yet.
Two other roommates -- who police said are not suspects -- survived and likely slept through the murders, according to officials. The survivors were on the ground floor while the four victims were on the second and third floors.
Police have said they have been searching for a white 2011-2013 Hyundai Elantra thought to have been near the home early on November 13.
Police said Thursday the rental home would be cleared of "potential biohazards and other harmful substances" to collect evidence starting Friday morning.
WATCH | New bodycam video shows Xana Kernodle talking to police weeks before murders
It was unclear how long the work would take, but a news release said the house would be returned to the property manager upon completion.
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 northern Idaho's Palouse region.
The case also enticed online sleuths who speculated about potential suspects and motives. In the early days of the investigation, police released relatively few details publicly.
Fears of a repeat attack prompted nearly half of the University of Idaho students to switch to online classes for the remainder of the semester, abandoning dorms and apartments in the normally bucolic town for the perceived safety of their hometowns.
Safety concerns also had the university hiring an additional security firm to escort students across campus and the Idaho State Police sending troopers to help patrol the city's streets.
This is a developing story and will be updated.
ABC News, the Associated Press and the CNN Wire contributed to this report