23% of U of I students are in organized Greek organizations:
Fraternity & Sorority Life | University of Idaho
There may be Greek ties to this crime, but that would be most likely due to 23% of the campus population participating (and it is probably well over 23% of the late night partying population). If a brother murdered another brother, there would be no incentive to cover up the crime. Who would want to live in a house with a murderer?
As to the murders themselves, we know LE was looking for large knife purchases. This type of knife could be used in hand-to-hand combat and are designed to kill strong young men rapidly - otherwise they would be of little military use. In more modern usage, this type of knife could be used to defend against a bear or other large predator. A few quick blows (or even a single stab) to the mid chest with a large knife would be likely to hit a major vascular structure causing rapid blood loss, loss of consciousness, and death. An injury a major bronchus could produce a rapid tension pneumothorax and death. A major lung injury could make it difficult to scream. With chest injuries, victims can exsanguinate into the chest
To me, the most likely scenario was a targetted attack against one of the two women on the third floor. The perp may have planned a quiet entry, quick kill, and rapid exit. When he attacks his victim as planned, in what was likely a darkened room, he was surprised when the second person wakes up and he has to silence her. Possibly there was enough noise to awaken E and X, and E confronts the perp coming down the steps and is stabbed. X may have witnessed this and becomes collateral damage. With his plan going sideways at this point, the perp heads out as quickly as possible.
As for the dog, possibly when the perp opened the door, the dog went outside and the door was closed behind him.
