Roommates of Slain Idaho Students 'Feel a Lot of Survivor's Guilt' About Murders: Source

Two of the victims' roommates were spared in the November attack

Ethan Chapin, Madison Mogen, Kaylee Goncalves and Xana Kernodle.

There are still more questions than answers in the November stabbing deaths of four University of Idaho students — and those who knew the victims are still struggling to make sense of the brutal murders.

Madison Mogen, Kaylee Goncalves, Xana Kernodle and Ethan Chapin were all stabbed to death in an off-campus rental home in Moscow, Idaho, on Nov. 13. A masked intruder entered the home and killed the four students with a fixed-blade knife, police say.

But two of the victims' roommates were unhurt during the rampage — and police say that they have been cleared as suspects. According to a police affidavit, one of the roommates said she saw the suspect as he left the scene.

The former roommates are still reeling from the murders and have been haunted by the events of that night.

"They feel a lot of survivor's guilt," a friend who has spoken to one of the roommates tells PEOPLE. "Their friends are gone and they're still here. It's been really rough on them. They're going to be dealing with this for the rest of their lives."

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A friend told NewsNation that one of the surviving roommates first heard noises around 4 a.m. on the morning of the murders. According to the news network, the roommate allegedly opened her door and yelled "calm down, you're being loud!" and "I'm trying to sleep!"

She then closed her door and locked it, the source tells NewsNation.

When she heard more loud noises, the roommate opened the door just in time to see the killer walking down the hall, the network reports.

More than a month later, authorities arrested Bryan Kohberger, a 28-year-old graduate student and teaching assistant at Washington State University. He was charged with four counts of murder and one count of felony burglary.

1122 King Road in Moscow, Idaho and Bryan Kohberger, the main suspect in the Idaho killings. David Ryder/Getty Images; Latah County Sheriff's Office/UPI/Shutterstock

The arrest has not provided closure to the former roommates.

"They've been interviewed by the cops about what they saw and heard," says the friend. "But they don't have all the answers. How can they? They are happy to be alive, but just so sad about it all. And wondering if they could've done anything differently. It's heartbreaking."

Kohberger has not yet entered a plea. His next hearing isn't until June 26. His attorney has not returned PEOPLE's messages for comment.