Really good theories discussed here.
I think the following 4 things make this case unusual and would need to be accounted for in a theory. (There are likely other factors but these 4 stood out to me).
1. The amount of physical exertion required to kill the first 2 people with a knife with repeated stabbing, hold onto the knife despite the extensive amount of blood, and then go and do it again with 2 more people.
[[ I think for the average person this is really over the top and stand by the idea that if this is one person he is fairly strong physically. The presence of two killers could help explain this part though if one person attacked each room .]]
2. The very disturbing psychology needed to do #1. Predatory. Callous. Determined. Narcissistic. Accustomed to the thought and act of violence.
[[ This really narrows down the % of people who could do this. Many people are killed by their significant other (sadly) but it is not in a typical person's psychology to kill 4 people especially with a knife which requires a lot of up close physical contact. If one girl rejected him (for example) and he killed 4 people as a result he is deeply narcissistic ]]
3. Doing all this without waking the roommates downstairs, without being clearly identified after the fact
[[ this to me speaks to a predatory nature. I think it's someone who would also hunt. Someone who enjoys plotting and watching. Who would plan all of this out, think ahead, be able to be fairly quiet. Comfortable using what is likely a hunting knife. ]]]
4. The fact that no one (to our knowledge) has come forward
[[ this one is also disturbing. Almost everyone is a part of a social circle even peripherally. Even the Unabomber was turned in by his brother. The longer this goes the smaller I think this person's circle would be and the more likely he is isolated. If not he would have reintegrated into daily life and not give himself away which is actually pretty hard. Most people would notice someone gone at 4am or see something suspicious in their behavior in the days after. Otherwise he would have to be someone who could disappear and not be missed. In many cases its the social circle of this person however peripheral who may be the key. ]]]
These 4 things are unusual, different from the Dateline episode type killing of a person by their significant other. I really don't believe that an average college student would have all 4 of these things covered. The amount of blood, the psychological horror of it, the physicality of it, the potential for adrenaline to lead to mistakes, the reintegration into their social circle could all lead to being caught.
All that being said I'm going with male older than college age , hunter, single, estranged from people. He either could disappear and no one would notice or people in his life already think he is odd so wouldn't pick up on additionally odd behavior.
I also don't think targeted means there isn't a threat to the community. He could easily have targeted one or more of the 4 and yet still be a danger if he decides to target someone else. A frightening question is after doing this will he want to do it again? Unfortunately I think it's likely. It's unlikely that a person would do something this extreme and then just walk away.
