Idaho student killings: suspect’s DNA allegedly matches knife sheath at scene

The suspect accused of murdering four University of Idaho students in their beds was linked to the slayings after authorities tested his family's household trash for DNA and found a match on a knife sheath at the scene, according to court documents released on Thursday.

The newly disclosed filing also portrays a chilling account of survival, with one roommate telling police that the mask-clad killer walked past her as he left.

Bryan Christopher Kohberger, 28, a criminology graduate student, landed on law enforcement radar after security camera footage near the house revealed a white sedan drove by their home four times shortly before the early-morning murders.

After the discovery , authorities released a "be-on-the-lookout" alert apprising law enforcement to watch for the vehicle.

A security officer at Washington State University - where Kohberger attended - happened upon a Hyundai Elantra matching the description. The officer ran the license plate, which has a Pennsylvania tag, and learned the vehicle was registered to Kohberger.

The owner's driver's license description matched the description provided by one of the surviving roommates, who according to court documents opened her bedroom door shortly after 4am on 13 November after she heard crying.

She saw a tall, white male "clad in black clothing and a mask that covered the person's mouth and nose walking towards her". She said he was about 5ft 10in or taller, with an athletic build and "bushy eyebrows".

As he strode past her, she said she stood in a "frozen shock phase". Authorities said they discovered a knife sheath alongside one of the victims which contained a "single source of male DNA".

A month after the murders, on 13 December, the car was detected on a Colorado license plate reader. Fox News reported that the FBI told local authorities in Indiana to pull the car over, with both Kohberger and his father inside, so that they could get a look at the suspect's hands.

Three days later, surveillance video on 16 December showed Kohberger in Pennsylvania. On 27 December, Pennsylvania authorities "recovered the trash" from his family's home in Albrightsville, then sent it to Idaho's crime lab, which matched it to DNA from the sheath with 99.9998% accuracy, according to court documents.

Kohberger was arrested early on 30 December by Pennsylvania state police at a home in Chestnuthill Township. He was extradited back to Idaho earlier this week.

The four students - Ethan Chapin, 20, Kaylee Goncalves, 21, Xana Kernodle, 20, and Madison Mogen, 21 - were fatally stabbed in an off-campus house near university sorority and fraternity houses. Autopsies revealed that all four were probably sleeping at the time. Each student was stabbed multiple times. Authorities said some had defensive wounds.

The quadruple murder rocked the community, with students and residents on edge for weeks as they waited for an arrest. Many of the university's 11,000 students departed the town of Moscow immediately after the killings, while others who left for Thanksgiving break decided not to return.