From motive, to how two roommates survived, many questions remain unanswered in the mysterious murders of four University of Idaho students.
"Everyone wants answers... we want to give those answers as soon as we can," Moscow Police Chief James Fry told ABC News on Wednesday, adding that some details must be withheld to protect the investigation.
MORE: Dad of slain Idaho student pleads with public for help: 'I have to have my justice'Here's what we know and what's still unclear:
Kaylee Goncalves, 21, her roommate and lifelong best friend, Madison Mogen, 21, another roommate Xana Kernodle, 20, and Kernodle's boyfriend Ethan Chapin, 20, were stabbed to death in the girls' off-campus house in the early hours of Nov. 13.
No suspects have been identified.
The murder weapon -- which police believe was a fixed-blade knife -- is still missing.
Chief Fry told ABC News on Wednesday that police "believe this is a targeted attack," but he wouldn't reveal why police think that. Fry would not say if a person or the house was a target.
But the Moscow Police Department contradicted that in a statement released just hours later.
MORE: Idaho murders: Victims' families speak at vigil, vow to 'get our justice'The statement said: "The Latah County Prosecutor’s Office stated the suspect(s) specifically looked at this residence, and that one or more of the occupants were undoubtedly targeted. We have spoken with the Latah County Prosecutor’s Office and identified this was a miscommunication. Detectives do not currently know if the residence or any occupants were specifically targeted but continue to investigate."
As to whether the killings were targeted, former FBI agent and ABC News contributor Brad Garrett said Thursday, "I don't think they [law enforcement] really know. I think they have theories, and maybe they're good theories about what happened. ... It certainly feels like, without knowing of course, that they don't know what they have."
Garrett isn’t involved in the investigation.
This wasn't the first miscommunication by local leaders.
Initially after the shocking murders, Moscow police said they believed there was "no imminent threat to the community," but later walked that back. Fry told ABC News Wednesday, "I own the messaging problem at the very beginning. We should've done a little better than that. ... we needed to correct that."
Garrett said high-profile cases put a lot of pressure on officials and it's "not uncommon" to see uncoordinated responses among the different agencies.
Police have not released a motive or potential profile of the killer.
Garrett said his guess is the attacker "really wanted to kill all four of them -- motive unknown and relationship to the victims unknown."
"Why would you go to the trouble to kill four people if in fact you're upset, angry or have revenge against one of them?" he said.
While Garrett doesn't know the motive, he said he believes the killer "likes to do these type of things and maybe has done it before."
He thinks the suspect is probably not in their late teens or early 20s because it's unlikely they could "methodically think through" four murders.
"Because of the time it would take, the energy it would take, and the focus that would take, it's a lot to ask of an 18-year-old," he said.
Two other roommates were in the house at the time and survived, likely sleeping through the attacks, according to police. The roommates are not considered suspects, police said.
The murders likely took place around 3 a.m. or 4 a.m., according to officials. In the morning, the two roommates called friends over because they thought one of the victims on the second floor had passed out and wasn't waking up, police said.
MORE: Idaho college murders: Timeline of eventsAt 11:58 a.m., a 911 call from one of the roommate's phones requested help for an unconscious person, police said. The 911 caller's identity has not been released but police said "multiple people talked with the 911 dispatcher."
Responding officers found the four victims on the second and third floors, police said.
Police said they do not believe anyone at the house at the time of the 911 call was involved.
As to how the surviving roommates could have slept through the murders, Garrett said the killer had the advantage of surprise, since the victims were likely asleep when he approached them. And the four victims "may have been killed in such a way it was difficult for them to scream," he said.
Police said all four victims were stabbed multiple times and were probably asleep when attacked.
As local, state and federal agencies continue to investigate, Garrett recommends they examine the "existing leads and go back over them regularly to see what you have missed."
"You then also have to expand this case -- and it sounds like they've done some of this -- because if you're dealing with a person who is a serial offender, then he has committed some version of this before," Garrett said. "Are there other stabbings of a similar nature? Maybe in a house at night?"
MORE: Idaho stabbing victim Ethan Chapin 'lived his best life' at collegeGarrett added, "You also have to keep the case in the public's eye, because you're always looking for new leads" and want to encourage people to submit tips.
Sometimes community members are reluctant to come forward with information "because they've had bad experiences with police or they're not sure what they know is really relevant," Garrett said.
"I would push the heinous nature of this crime," Garrett said, and stress that police need the community's help to "get this person off the street."
The University of Idaho community is on edge in the wake of the slayings, and the police department said it's received an influx of 911 calls.
Garrett said he would tell concerned students: "What happened on your campus is extremely rare. The odds of you being in harm's way is, relatively speaking, low."
But he urges them to stay aware of their surroundings.
"Don't walk alone," he said. "Super-secure everything: the windows, the doors."
The police chief promised to ABC News on Wednesday that the department won't allow the case to go cold.
"We're going to work continuously. And we're going to provide as many answers as we can, and we're going to do the best job we can," he said.
Police urge anyone with information to upload digital media to fbi.gov/moscowidaho or contact the tip line at tipline@ci.moscow.id.us or 208-883-7180.