Dylan Mortensen, 21, told police she saw a masked figure clad in black walk pass her at 4am on the night the four students were killed, but didn’t call 911 for another eight hours.
Shannon Gray, who represents Kaylee Goncalves’ family, told Fox News that Ms Mortenson was “scared to death, and rightly so”.
“This guy had just murdered four people in the home,” Ms Gray told Fox News.
Mr Kohberger, 28, has been charged with the murder of Goncalves and Madison Mogen, 21, and Xana Kernodle and her boyfriend Ethan Chapin, both 20.
Ms Mortensen, identified by her initials DM in the police affidavit, said she had awoken on the night of the killings to hear what sounded like Goncalves playing with her dog.
Shortly afterwards, she recalled hearing one of her roommates saying “there’s someone here”.
She said she went to look out of her door, and heard a man’s voice saying: “It’s OK, I’m going to help you.”
A few minutes later, she came face-to-face with “a figure clad in black clothing and a mask that covered the person’s mouth and nose walking towards her”.
The man had bushy eyebrows, she recalled.
Ms Mortensen said she froze as the suspect walked past her and headed toward the back sliding glass door of the home.
Police believe the murders were carried out between 4am and 4.25am on 13 November.
After encountering the intruder, Ms Mortensen and another roommate locked themselves in their room until midday.
After questions were raised about the length of time it took to summon police to the Moscow address, Ms Gray stressed that Ms Mortensen was also a “victim”.
“Everybody kind of forgets that,” she told Fox News.
“The Goncalves family doesn’t have any ill will towards her or anything like that.”
The affidavit also revealed that police had tied Mr Kohberger to the killings after DNA was allegedly found on a knife sheath left at the home.
Cellphone data showed that he had “stalked” the home a dozen times in the weeks leading up to the murders, and had returned to the scene around five hours after they were committed.
Mr Kohberger owned a white Hyundai Elantra spotted on surveillance camera close to the students’ home, police said.