(CNN) — With the investigation into the killings of four University of Idaho students in the town of Moscow now entering its second week, authorities say efforts to find the culprit in the attack are ongoing.

“We’re trying to expedite everything that might possibly lead to a suspect,” Latah County prosecutor Bill Thompson said Saturday.

The four students killed — Ethan Chapin, 20; Kaylee Goncalves, 21; Xana Kernodle, 20; and Madison Mogen, 21 — were discovered by police last Sunday in an off-campus home. The victims were stabbed to death, according to a county coroner, and the weapon used has yet to be found.

Thompson was one of several officials who spent about two hours at the crime scene Saturday as a part of the active investigation.

“I wish we had more answers, and they’re still asking questions,” Thompson said.

With a town and campus community increasingly concerned over the homicides and lack of answers in the case, many students have left Moscow ahead of the fall break. Police clarified last week they were unable to determine if the public was at greater risk.

“We cannot say there’s no threat to the community and as we have stated, please stay vigilant, report any suspicious activity and be aware of your surroundings at all times,” Moscow Police Chief James Fry said Wednesday.

Many professors canceled classes last week, including Zachary Turpin, who wrote on social media he “can’t in good conscience hold class” until police release more information or identify a suspect in the murders.

The Moscow Police Department is leading the investigation with assistance from the FBI as well as state and local law enforcement agencies. In a Friday night statement, Moscow police said investigators had completed 38 interviews with people “who may have information about the murders.”

Local businesses have been contacted by detectives “to determine if a fixed-blade knife had been recently purchased,” Moscow police said. Three dumpsters located on a street near the home were also retrieved to search for potential evidence, according to the statement.

An email tip line was provided for those in the area to help with any information. Detectives were working on processing nearly 500 tips received as of Friday late afternoon, police added.

Police working to fill in timeline

Investigators this week have started to build a timeline of events regarding the students and their last known whereabouts before the fatal attack.

Chapin and Kernodle attended a party at the Sigma Chi fraternity house from 8 p.m. to 9 p.m. Saturday.

Goncalves and Mogen were at a local sports bar between 10 p.m. and 1:30 a.m. The pair was then seen ordering from a nearby food truck, according to a live Twitch stream from the truck.

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. Investigators do not believe the driver was involved in the deaths, police said Saturday.

From there, authorities are working to determine how and when the attack transpired.

According to Moscow police, it was not until just before noon Sunday when a 911 call was received about an “unconscious individual,” and responding officers found the four students killed. Police have said there were no signs of forced entry when officers arrived.

One of the doors used to access the home has a keypad lock which requires a code to gain entry, according to Jeffrey Kernodle, Xana Kernodle’s father.

Goncalves’ sister, Alivea Goncalves, said the residence was known to be a “party house,” thus some previous visitors may have had access.

“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, which could have been used to gain entry, Jeffrey Kernodle told CNN affiliate KPHO/KTVK.

The 911 call came from a phone belonging to one of the two surviving roommates, police said Saturday.

The two were at the home during the attack and were not injured. Moscow police “do not believe” the two were involved in the crime, the department said Friday.

The students were “likely asleep” before being attacked, Moscow police said Friday, citing the Latah County coroner. Some of the four had defensive wounds — though it is not specified how many victims did — and there were no signs of sexual assault, according to the police update.

Earlier this week, Jeffrey Kernodle told KPHO/KTVK his daughter fought off her attacker through the very end, saying the autopsy report showed, “Bruises, torn by the knife. She’s a tough kid.”

Alivea Goncalves told the New York Times there were seven unanswered calls made from her sister’s phone to her former boyfriend between 2:26 a.m. and 2:52 a.m., based on information from phone logs Alivea Goncalves was able to download from her sister’s phone provider.

She told the New York Times the frequency of the calls was not unusual, and her sister would often call people repeatedly until they answered the phone.

CNN has made numerous attempts to contact Alivea Goncalves. The boyfriend’s mother told CNN on Saturday she had no comment out of respect for the wishes of the Goncalves family.

Vigil will be held next week

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 encouraging 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.”