FIRST ON FOX: MOSCOW, Idaho - Investigators returned to the Idaho home Friday where four college students were stabbed to death in their sleep earlier this month.
Police and members of the FBI first looked outside and walked up the hill behind the home, which is built into a slope and stands three stories tall.
Next they came back down and were seen putting on protective covers over their shoes and returning inside the home on King Road, which had been untouched for days.
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Kaylee Goncalves, 21; Madison Mogen, 21; Xana Kernodle, 20; and Ethan Chapin, 20, were found dead hours after police say someone attacked them in their sleep on Nov. 13.
The three women lived there and Chapin was visiting his girlfriend, Kernodle. Authorities have said they found no signs of forced entry.
Two of the victims were sleeping on the second floor, and two were on the third.
All four attended the University of Idaho.
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Chapin was a member of the Sigma Chi fraternity, the University of Idaho said earlier this month. Kernodle and Mogen were both part of the Pi Beta Phi sorority, and Goncalves belonged to Alpha Phi.
Investigators on Friday could be seen through the upstairs windows analyzing the interior.
They were also seen looking just inside the front door on the bottom floor. Two roommates on the ground level and a pet dog were unharmed in the attack.
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After searching the inside of the house, one of the investigators left with several small paper bags in his hand.
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"Detectives continue investigating and will collect evidence," Aaron Snell, the communications director for the Idaho State Police, told Fox News Digital. However, he added that he did not have details about what authorities removed from the scene Friday afternoon.
Investigators were looking into all possibilities 12 days after the attack, according to authorities, who worked through Thanksgiving Day and Black Friday.
Most students have left town for the Thanksgiving holiday, but University of Idaho President Scott Green has said that all students will have the option to finish the semester remotely.
Police have not yet identified a suspect or recovered the murder weapon - believed to be a fixed-blade knife. All four victims had been stabbed to death, and some had defensive wounds, according to authorities.
But police say they've ruled out the two female roommates who were downstairs at the time of the murders, a man who appeared on surveillance video at a food truck at the same time as Goncalves and Mogen shortly before they returned from a night out, a "private party" driver who took them home, Goncalves' ex-boyfriend and a group of friends who were present at the house Sunday morning when the initial 911 call was placed.
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Police say they believe the attack was targeted and are asking the public for information and surveillance video.
They are also looking into a claim that Goncalves may have had a stalker.
Anyone with information on that topic is also asked to reach out to police - no matter how small the details may be.
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"We continue looking into the stalker issue and are asking for any information from the public on this topic," Snell said.
Anyone with information on the stalker or on the case in general is asked to call the tip line at 208-883-7180 or email firstname.lastname@example.org.