Idaho cops on college murder mystery grind out overtime as two-week mark nears without a suspect

MOSCOW, Idaho - EXCLUSIVE PHOTOS: Nearly two weeks after four college friends were found brutally stabbed to death at a rental house just yards away from the University of Idaho campus in Moscow, police have been working around the clock for days trying to crack the case.

Kaylee Goncalves, 21; Madison Mogen, 21; Xana Kernodle, 20; and Ethan Chapin, 20, were found dead on two separate floors of a three-story house, hours after police say someone attacked them in their sleep on Nov. 13. The three women lived there, and the visiting Chapin was Kernodle's boyfriend.

On Friday, detectives and FBI investigators returned to the crime scene, examined both the interior and exterior, and left with several small bags. 

Then they returned to the Moscow police station, where they met with Latah County Prosecutor Bill Thompson and Moscow Police Chief James Fry for about an hour after sundown.

IDAHO MURDERS: DETECTIVES, FBI RETURN TO CAMPUS STABBING SCENE, COLLECT EVIDENCE AND MEET WITH THE PROSECUTOR

Police Chief James Fry leaving Moscow, Idaho police station on Black Friday. (Derek Shook for Fox News Digital)

Moscow's last homicide occurred in 2015. Since the quadruple murder, dozens of federal and state law enforcement officials have been assigned to the case to assist city police in identifying and finding the killer, as well as the killer's motive.

Officials are also still searching for the murder weapon, which they believe to be a knife. They have received and analyzed more than 1,000 tips related to the case.

At the state crime lab in Boise, Idaho State Police (ISP) Forensic Services have been handling the majority of the forensics analysis, in the case, which is a "priority for them," ISP Public Information Officer Aaron Snell told Fox News Digital in a Friday interview.

Latah County Prosecutor Bill Thompson working after dark on Black Friday. (Derek Shook for Fox News Digital)

"There have been scientists working 24/7 in the lab to try and get back some of those results in quick order," Snell continued. "So, while there's other cases going on, this case is a priority. And we're starting to get back some results."

IDAHO STATE CRIME LAB PRIORITIZES EVIDENCE TESTING IN COLLEGE STUDENTS' BRUTAL MURDER CASE

Those results are being sent to detectives in real time, he said, as they work to narrow down one or more suspects in the massacre.

There were no signs of forced entry at the victims' residence, which was known among neighbors as a loud party house for U of I students, but the crime scene was very bloody when police arrived shortly after receiving a 911 call reporting an unconscious person at 11:58 a.m. that morning.

It is unclear exactly how many people — in addition to the victims' two surviving roommates — were at the home before police arrived.

IDAHO MURDERS: INVESTIGATORS WORK THROUGH THANKSGIVING DAY AS COLLEGE TOWN SHUTS DOWN

Police have kept quiet about crime scene specifics to protect the integrity of their ongoing investigation. But while they've gone 13 days without naming a suspect, they say they've collected important crime scene evidence in the home and that there are details in the 911 call that they are keeping confidential for the time being.

Latah County Prosecutor Bill Thompson working after dark on Black Friday. (Derek Shook for Fox News Digital)

"We're going to be patient. We're going to be thorough. And…we also ask that the community recognize that there are some aspects of this investigation that will take us a little bit longer, but we're going to continue to work through," Snell said.

WATCH: Had Idaho murderer been inside the victims' house in the past?

Chapin was a member of the Sigma Chi fraternity, majoring in recreation, sport and tourism management, the University of Idaho said. Kernodle and Mogen were both part of the Pi Beta Phi sorority and were marketing majors. Goncalves, a general studies major, belonged to Alpha Phi.

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University of Idaho students will have the option to take remote classes as the perpetrator remains on loose. 

Police are asking anyone with information or footage related to the slayings to call 208-883-7180 or tipline@ci.moscow.id.us.

Fox News' Emmett Jones contributed to this report.