BOISE, Idaho -- DNA allegedly found on a knife sheath recovered at the murder scene.
A roommate described a masked figure with "bushy eyebrows."
Phone records showed the suspect was near the victims' residence numerous times in the months before the killings.
Nearly two months after the killings of four University of Idaho students captivated the country and sowed fear in the small community of Moscow, Idaho, an affidavit released Thursday offered a look at the investigative work that went into identifying Bryan Kohberger as the suspect.
The 28-year-old PhD student in criminal justice was extradited to Idaho Wednesday from his home state of Pennsylvania. Facing four counts of first-degree murder and one count of burglary, Kohberger did not enter a plea during his initial court appearance Thursday.
The suspect was arrested in Pennsylvania December 30, nearly seven weeks after Kaylee Goncalves, 21; Madison Mogen, 21; Xana Kernodle, 20; and Ethan Chapin, 20, were found fatally stabbed in an off-campus home.
Here are key takeaways from the court documents -- which include the probable cause affidavit used to support Kohberger's arrest and obtain a warrant -- and some questions that remain.
DNA allegedly found on a knife sheath at the crime scene
Trash recovered from the Pennsylvania home of Kohberger's family late last month and sent to the Idaho State Lab for DNA testing revealed that the "DNA profile obtained from the trash" matched a tan leather knife sheath found "laying on the bed" of one of the victims, according to the probable cause affidavit.
The DNA in the trash "identified a male as not being excluded as the biological father" of the suspect whose DNA was found on the sheath.
"At least 99.9998% of the male population would be expected to be excluded from the possibility of being the suspect's biological father," the affidavit said.
Roommate saw a figure dressed in black clothing and a mask
One of two roommates who were not harmed told investigators she saw a masked man dressed in black in the house the morning of the attack, according to the probable cause affidavit.
Identified in the document as D.M., the roommate said she "heard crying" in the house that morning and a male voice saying, 'It's OK, I'm going to help you.'"
D.M. told investigators she saw a "figure clad in black clothing and a mask that covered the person's mouth and nose walking towards her," according to the affidavit.
"D.M. described the figure as 5' 10" or taller, male, not very muscular, but athletically built with bushy eyebrows," the affidavit said. "The male walked past D.M. as she stood in 'frozen shock.'"
"The male walked towards the back sliding glass door. D.M. locked herself in her room after seeing the male," according to the document, which said the roommate did not recognize the male.
Surveillance video pointed to a white sedan
Authorities reviewed local surveillance footage and were drawn to a white sedan, later identified as a Hyundai Elantra, according to the affidavit.
The vehicle was seen in the area around the home where the killings took place.
By November 25, local law enforcement had been notified to be on the lookout for the vehicle, the affidavit said.
Days later, officers at nearby Washington State University, where the suspect was a PhD student in criminal justice, identified a white Elantra and found it was registered to Kohberger.
Kohberger's driver's license information was consistent with the description the unharmed roommate gave investigators, according to the affidavit.
The document specifically noted Kohberger's height and weight -- 6 feet and 185 pounds -- and that he has bushy eyebrows.
White Elantra at the Pennsylvania home of Kohberger's parents
Kohberger received a new license plate for his Elantra five days after the killings, the affidavit said, citing records from the Washington State Department of Licensing.
At the time of Kohberger's arrest last week, a white Elantra was found at his parents' house in Pennsylvania, according to Monroe County Chief Public Defender Jason LaBar, who said Kohberger had gone home for the holidays.
Suspect's phone used at least a dozen times near the students' residence
Phone records show Kohberger's phone was near the victims' residence at least 12 times since June, according to the court documents.
"All of these occasions, except for one, occurred in the late evening and early morning hours of their respective days."
Additionally, records show Kohberger's phone was near the murder scene -- 1122 King Road -- between 9:12 a.m. and 9:21 a.m. -- hours after the killings, according to the court documents.
A review of phone records showed Kohberger's phone left his home at approximately 9 a.m. and traveled to Moscow, the affidavit said, and that the same phone traveled "back to the area of the Kohberger Residence ... arriving to the area at approximately 9:32 a.m."
Perspectives from the experts
Prominent Philadelphia defense attorney Fortunato Perri Jr. and retired FBI agent Laura Zartman are not involved in the case but both reviewed the newly unsealed affidavit.
Both agree DNA and the tracking of Kohberger's phone were key to the investigation.
"Very quickly after that they got DNA from the Pennsylvania house -- that's when they could conclusively say 'aha," explains Zartman.
Cell phone tracking helped police solidify the movements of the white Hyundai Elantra near the victims' homes on the night of the murders, and the weeks leading up to the crimes.
"It certainly could go to trial. I've seen cases with overwhelming evidence and the client still wants to have their day in court," said Perri. "Although the investigation conducted was exhaustive it doesn't look like it's that sophisticated of a case to put forward to a jury."
Suspect applied for a police internship in 2022
Kohberger applied for an internship with the Pullman Police Department in Washington in the fall of 2022, court documents show.
"Pursuant to records provided by a member of the interview panel for Pullman Police Department, we learned that Kohberger's past education included undergraduate degrees in psychology and cloud-based forensics," according to an affidavit.
"These records also showed Kohberger wrote an essay when he applied for an internship with the Pullman Police Department in the fall of 2022. Kohberger wrote in his essay he had interest in assisting rural law enforcement agencies with how to better collect and analyze technological data in public safety operations."
Still, questions remain
Nearly two months after the killings, however, a number of questions remain.
It's not clear why the unharmed roommate did not immediately call 911, or why the roommates were spared.
The motive for the crime also remains a mystery, and police have said they are still looking for the murder weapon.
The documents released Thursday shed no light on whether Kohberger had any other reason to be in the area at the time of the killings.
Why wasn't Kohberger arrested until more than six weeks after the victims were found dead?
And authorities have not said publicly whether Kohberger knew any of the victims.
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