One of the two roommates who survived the University of Idaho murders said she came face-to-face with the killer, who is suspected to be Bryan Kohberger. But many are now wondering why she did not call the authorities immediately after the chilling encounter. 

According to a police affidavit that was made public Thursday, Dylan Mortensen, 21, described her terrifying encounter with the suspect dressed in all black when she opened her bedroom door after hearing a noise shortly after 4 a.m.

Mortensen, who lived through the attack with Bethany Funke, noted that the black-clad figure was wearing a mask that covered his mouth and nose.

She also told police that she heard one of her housemates say: "There's someone here."

She said the 5′ 10″ tall male, who is "not very muscular, but athletically built with bushy eyebrows," walked past her as the man approached the back sliding glass door, and she stood in a "frozen shock phase."

Mortensen told cops that she heard the man say,"'it's ok, I'm here to help you," and let her survive as well as Funke.

Mortensen said she locked herself in her room after seeing the man who wandered the house committing the crime. The roommate still did not call the police at the time.

Authorities noted that a 911 call was only made by one of the surviving roommates at 11:58 a.m., reporting an unconscious person. However, it was not revealed who spoke to the police.

It was also not explained why Mortensen did not contact authorities for more than seven hours, despite hearing several scuffles and a roommate crying and seeing the killer. 

Aside from the two roommates, the killer also spared Kaylee Gonclaves' dog.

The affidavit also included details of how Bryan Kohberger's DNA was found on a knife sheath lying close to the bodies of Gonclaves and Maddie Mogen.

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Idaho Murder Victims Targeted by Bryan Kohberger

It was not immediately clear why Bryan Kohberger targeted the four students and left two of their roommates to live.

Authorities tracked Kohberger through his phone, but law enforcement officials have yet to state how he knew the students in the first place.

Kohberger's classmates said the suspect continued to attend classes after the killings and even finished the fall semester.

The released affidavit also noted that police tried to identify whether Kohberger stalked any of the victims before the murder.

Law enforcement officials also conducted surveillance on the King Road residence in Moscow and were in contact with any of the victims' associates before or after the alleged offense.

The affidavit does not elaborate on how the students came to Kohberger's radar. It only noted that the Ph.D. student of Washington States University had stalked them for some time in the "early morning and late evenings."

Kohberger was allegedly staking out the students' home on 1122 King Road on at least 12 occasions before the killings.

Police detail his every move on the day of the murders, helped by surveillance footage of the suspect's car and cell site data from his phone.

Idaho Murders Weapon

Authorities have yet to locate the weapon used in the killings of the four roommates.

Law enforcement officials said they would remain silent on what information they could share with the public since it is still an ongoing investigation.

Chief Moscow Police James Fry appealed to the public for information regarding the whereabouts of the murder weapon. Only the sheath of a knife was discovered at the scene.

The sheath was described as "tan leather" with the United States Marines Corps and "KA-BAR" insignia stitched on its exterior.

Police officials allowed a garbage truck filled with trash to collect a dumpster from the house before it had been searched.

The prosecutor for Latah County, Bill Thompson, noted that it is not the end of the investigation.

Fry said no arrests would ever "bring back these young students." He added that they believe justice will be found "through the criminal process." Police have yet to state the possible motive behind the crime.

College students Mogen, 21; Goncalves, 21; Xana Kernodle, 20; and Ethan Chapin, 20, were found stabbed to death in their beds on November 13.

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This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Chilling New Details in Idaho Student Murders - From CBS Evening News