Idaho investigators may be probing whether the killer hid in the woods before entering the victims' off-campus home and slaughtering them with a knife, Fox News Digital has learned.
Police said they have not identified any suspects or determined whether there was more than one assailant in the grisly Nov. 13 attack on Kaylee Goncalves, Madison Mogen, Ethan Chapin, and Xana Kernodle.
On Monday, a cluster of FBI agents and Idaho State Police officers were seen behind the three-story home on King Road trying to peer through the third-floor windows of Mogen's room, which showcase a pair of pink cowboy boots.
Police have said that the victims were murdered on the second and third floors.
"They can look from the bushes and see a lot when the house is illuminated at night. That's troubling," said professor Joseph Morgan, distinguished scholar of applied forensics at Jacksonville State University. Morgan is not involved in the case but is following it closely.
King Road passes in front of the home then curves right up a steep hill and terminates in a parking lot behind the house. The parking lot belongs to an apartment located to the left of the house.
Law-enforcement officers were seen crouching behind the trees that separate the parking lot from the house, looking for the best vantage point. They were about 10 yards from the home.
Investigators were also seen looking for any depressions in the ground perhaps left by the suspect lying in wait.
A law enforcement source told Fox News that authorities are investigating the possibility of a peeping Tom. Idaho State Police Communications Director Aaron Snell would only say that investigators are exploring all theories.
Earlier Monday, police temporarily expanded the crime scene to include the wooded area and the parking lot behind the house.
Investigators appeared to be exploring the killer's possible exit route.
A group of law-enforcement agents stood in the parking lot as an Idaho State Police officer sprinted toward them from the home's back sliding doors using two different routes.
Mogen, Kernodle and Goncalves lived in the six-bedroom home – along with two other roommates who were there during the attack but were unharmed.
Police have cleared them as suspects. Chapin, who was dating Kernoodle, was staying the night.
Audrey Conklin, Stephanie Pagones and Cristina Corbin contributed to this report.