Bryan Kohberger bought a Ka-Bar knife and knife sheath from Amazon seven months before he allegedly stabbed four University of Idaho students to death in a brutal attack that sent shockwaves across America, it has been revealed.
NBC’s Dateline special “The Killings on King Road” reported that the 28-year-old accused killer shopped online for the military-style knife in April 2022.
At the time, he was still studying for his master’s degree in criminology at DeSales University in Pennsylvania.
He graduated from the university that June and then relocated across the country to Pullman, Washington, where he began a graduate program in criminal justice at Washington State University.
The report indicates that Mr Kohberger took the knife with him when he moved.
On 13 November, he allegedly used either that knife or a similar one to stab Madison Mogen, Kaylee Goncalves, both 21, and Xana Kernodle and Ethan Chapin, both 20, to death in an off-campus home in Moscow, Idaho.
Investigators tied Mr Kohberger to the murders after the killer left a Ka-Bar knife sheath behind at the scene next to Mogen’s body.
DNA found on the sheath matched that of the 28-year-old PhD student, according to the criminal affidavit.
The murder weapon itself has never been found.
Former FBI profiler Greg Cooper told Dateline that the knife purchase coming months before the murders indicates that the suspect “had a fantasy of thinking about committing crimes for a long time with that knife” prior to the moment he allegedly used it.
The NBC special also revealed for the first time that Mr Kohberger’s own family allegedly had suspicions of his possible involvement prior to his arrest and that he may have broken into another female student’s home in the lead-up to the murders.
The 28-year-old criminology PhD student had befriended the woman after he moved to Pullman, according to a source.
One day, the woman returned to her apartment and found that someone had broken in and moved items around the home – but that nothing was missing.
Since nothing was taken, the woman decided not to call the police but instead called her new friend Mr Kohberger and asked him to come over.
Mr Kohberger allegedly offered to install a video security system inside her home and the woman agreed.
Following its installation, investigators believe Mr Kohberger used the security cameras to spy on the woman as – knowing her wifi password – he was able to tap into the cameras when within close proximity to the apartment.
Mr Cooper told Dateline that the incident was a “step in progression” for Mr Kohberger to move from breaking into a home when no one was in to allegedly breaking in when multiple people were home at the King Road address that deadly night in November.
In the Dateline episode, sources also revealed that Mr Kohberger’s sister was growing suspicious that her brother could have been responsible for the murders when the family gathered to spend the holidays together.
In mid-December, Mr Kohberger left Pullman to travel cross country with his father back to the family home in Albrightsville, Pennsylvania, for the holidays.
During his time at home, his family members noticed that he was behaving somewhat bizarrely.
The source said that Mr Kohberger was constantly wearing latex gloves, including inside their own home.
One of his two older sisters began to wonder if he could have played a part in the murders – and, at one point, she raised her concerns with her other family members.
She “loudly pointed out” that, at the time of the murders, her brother was living just a few miles from the crime scene and that he drove a white Hyundai Elantra – the make and colour of vehicle at the centre of the investigation.
Along with his bizarre tendency to wear latex gloves at all time, she believed that the family should consider that Mr Kohberger might have killed the four victims, the source said.
Mr Kohberger’s father allegedly defended his son and insisted he could not have been involved.
But her suspicions were so great that – at one point – several family members searched Mr Kohberger’s white Hyundai Elantra for possible evidence of the crime, the source said.
By that point, police said Mr Kohberger had already been spotted cleaning his car out with bleach and so the family members didn’t find anything of note, the source said.
It is not clear if Mr Kohberger was aware of his family members’ suspicions that he could have been behind the murders – or what potential prior behaviour may have led his own sister to suspect him capable of carrying out such a brutal crime.
Soon after, in the early hours of 30 December, law enforcement swooped on the family home and arrested him for the murders.
At the time of his arrest, the source said Mr Kohberger was wide awake standing in the kitchen wearing latex gloves and putting his personal trash in plastic bags to take it out to a neighbour’s trash can.
An attorney close to Mr Kohberger’s family declined to comment on the revelations to Dateline.
On Monday (22 May), he will appear in court for his arraignment on four counts of first-degree murder and burglary.
The 28-year-old is now scheduled to be arraigned in Latah County Court in Moscow, where he is expected to enter a plea on the charges.
Mr Kohberger had been due to appear in court for a week-long preliminary hearing on 26 June, where the prosecution would lay out the case and evidence against the suspect.
However, on 16 May, a grand jury indicted Mr Kohberger on the charges, paving the way for the case to proceed without and leading to the cancellation of the preliminary hearing.
Mr Kohberger is accused of breaking into the student home in the early hours of 13 November and stabbing the four students to death in a horror attack that rocked the college town of Moscow and sent shockwaves across America.
The motive remains unknown and it is still unclear what connection the WSU PhD student had to the University of Idaho students – if any – prior to the murders.
However, the affidavit, released in January, revealed that Mr Kohberger’s DNA was found on a knife sheath left behind at the scene of the murders.
It also revealed that his white Hyundai Elantra was caught on surveillance footage at the crime scene and that one of the surviving roommates came face to face with the killer – masked, dressed in head to toe black and with bushy eyebrows – as he left the home in the aftermath of the murders.
New details have also emerged about what was found during an initial search of his apartment and a rental storage unit.
The court documents show that two items found in his apartment tested positive for blood.
The two items were a mattress cover on the bed and an uncased pillow, both of which had visible “reddish brown stains”.
The documents do not reveal who the blood belongs to.
Investigators seized a string of other items from his home including possible human and animal hair strands, a disposable glove and a computer.
The murder weapon – a fixed-blade knife – has still never been found.
As a criminal justice PhD student at WSU, Mr Kohberger lived just 15 minutes from the victims over the Idaho-Washington border in Pullman. He had moved there from Pennsylvania and began his studies there that summer, having just completed his first semester before his arrest.
Before this, he studied criminology at DeSales University – first as an undergraduate and then finishing his graduate studies in June 2022.
While there, he studied under renowned forensic psychologist Katherine Ramsland who interviewed the BTK serial killer and co-wrote the book Confession of a Serial Killer: The Untold Story of Dennis Rader, the BTK Killer with him.
He also carried out a research project “to understand how emotions and psychological traits influence decision-making when committing a crime”.
Now, the criminology PhD student is set to appear in Latah County Courthouse in Idaho for his preliminary hearing on 26 June.
He is facing life in prison or the death penalty for the murders that have rocked the small college town of Moscow and hit headlines around the globe.