The four students -- Ethan Chapin, 20; Kaylee Goncalves, 21; Xana Kernodle, 20; and Madison Mogen, 21 -- were found Sunday stabbed to death on the second and third floors of the home in Moscow, Idaho, according to authorities.
[Ads /]
Key details on how the gruesome attacks unfolded remained unclear Friday even after the Moscow Police Department provided an update into the extensive investigation that includes federal, state and local law enforcement agencies.
Police revealed the four victims were "likely asleep" before the attack began during the early morning hours Sunday and each was stabbed multiple times. The attacks were not reported to authorities until around noon that day, police have said.
A week after the homicides shook the small college city of some 26,000 residents, investigators have not identified a suspect nor did they find the murder weapon used to carry out the heinous attacks.
Here's what we know -- and still don't know -- as the investigation continues.
How the physical struggle unfolded remains unclear
All four victims' killings were ruled homicides by stabbing, according to Latah County Coroner Cathy Mabbutt. Of the victims, "some had defensive wounds," Moscow police said in their most recent update Friday.
But it's unclear how many of the victims or which victims precisely had defensive wounds.
Earlier this week, the father of Xana Kernodle revealed that his daughter fought off her attacker through the very end.
"Bruises, torn by the knife. She's a tough kid," Jeffrey Kernodle told CNN affiliate KPHO/KTVK in Avondale, Arizona.
When Mabbutt arrived to the crime scene, she saw "lots of blood on the wall," she told CNN.
Each victim was stabbed multiple times -- likely by the same weapon, Mabbutt said, stopping short of specifying how many wounds or where most were located.
Moscow police also pointed out Friday that the victims were not "tied and gagged" during the attack. The victims' autopsies did not find signs of sexual assault, Mabbutt said.
Method of entry, weapon still question marks
When police arrived at the home after they received a 911 call, the door was open and there was no damage inside, Moscow Police Chief James Fry said. There was no evidence of forced entry, he said.
One of the doors used to access the home has a keypad lock that requires a code to gain entry, according to Jeffrey Kernodle.
Alivea Goncalves -- Kaylee's sister -- noted the residence was known to be a "party house" and had been for some time.
[Ads /]
"So I won't say they were very private with that code," Goncalves told ABC World News Tonight.
The house also has a sliding door that could have been used to gain entry, Jeffrey Kernodle told KPHO/KTVK.
Along with the lack of suspect identification, police have yet to locate the murder weapon used.
To that end, investigators have requested from local businesses information on any recent purchases of a "fixed-blade knife." Moscow police did not provide further information on those details.
Timeline under analysis
Hoping for tips from the community, investigators on Friday released a map and timeline of the victims' movements last weekend. The map shows the four students spent most of the night separated in pairs.
Chapin and Kernodle attended a party at the Sigma Chi fraternity house from 8 p.m. to 9 p.m. local time Saturday.
Goncalves and Mogen were at the Corner Club sports bar between 10 p.m. and 1:30 a.m. The pair was then seen ordering from a food truck, according to a live Twitch stream from the truck.
2 other roommates were home during Idaho students' murders, police say
As they waited for about 10 minutes for their food, they chatted with each other as well as other people standing by the truck. The man who manages the truck told CNN the pair did not seem to be in distress or in danger in any way.
Goncalves and Mogen used a "private party" for a ride, arriving home at 1:45 a.m, police said in their update. All four victims were back at the house by about 1:45 a.m. Sunday.
Surviving roommates could be 'key to this whole thing'
Two other roommates were home at the time of the attack and were found uninjured, Fry said earlier this week. Moscow police "do not believe" the two surviving roommates or a man seen in the food truck surveillance video were involved in the crime, the department said Friday.
Aaron Snell, the communications director for Idaho State Police, told ABC that the surviving roommates could provide some significant leads in the investigation.
"Potentially they are witnesses, potentially they are victims," Snell said in an interview with ABC's Kayna Whitworth. "Potentially they're the key to this whole thing."
[Ads /]
Authorities hope the roommates will be able to help them "figure out what occurred and why," Snell said.
"That's their story to tell," he said. "No one has been ruled included or excluded as a person of interest and/or a suspect. Everyone is still being investigated," he stated.
38 interviews conducted so far
Police have said they received a 911 call around noon Sunday reporting an unconscious person at the home. The caller has not been identified.
By Friday late afternoon, investigators had completed 38 interviews with people "who may have information about the murders," Moscow police said.
Authorities also seized items from three dumpsters near the house to review for potential evidence, police said Friday. No further updates of the search have been disclosed.
Detectives were working on processing nearly 500 tips received as of Friday late afternoon, police added, and Moscow police is leading the investigation with help from the Idaho State Police, the Federal Bureau of Investigation and the Latah County Sheriff's Office.
University officials have provided an email tip line to Moscow police Friday.
Vigil planned following Thanksgiving break
The university announced a candlelight vigil will be held in remembrance of the four students killed.
The vigil will take place on campus on November 30, according to the university Friday, and those who are not able to attend in person are invited to also take part in the ceremony.
"Please join us from where you are, individually or as a group, to help us light up Idaho. Light a candle, turn on stadium lights, or hold a moment of silence with us as we unite on campus," the university said. The vigil would be held after the Thanksgiving break to give more people the opportunity to attend.
University of Idaho President Scott Green sent a memo on Thursday that encouraged students to follow their best course of action as the university community processes the homicides.
"We need to remain flexible this week and grant our students and colleagues room to process these unprecedented events in their own way," Green said. "Students, you are encouraged to do what is right for you. Whether this is going home early or staying in class, you have our support.