TG - there are NO good predictive signs that don't generate many false positives.
The best we have is:
1. Owning weapons and a fascination with such (oh, dear)
AND
2. Making threats
That should get you a close look. The causal factors that lead to a rampage are not good predictors as for most they are unknowable by others before the rampage. We do know that seemingly arbitrary disciplinary actions that disrespect unstable people can be a prime for violence. As is bullying (more a high school thing). Coupled with depression or other disorders gives you a dangerous package but that is in a small percent of those who have gone through such. Schools are reluctant to deal with bullying because sometimes the bullying is done by the value 'alpha' males of the school.
To get folks to turn in folks who show the two signs is difficult. Young people are very oriented towards social groups and reluctant to turn in peers. Schools are reluctant to act because of civil rights concerns and law suits.
Let's say the next professor gets a paper on student carry but in the body of the paper - the kid sounds disturbed in some manner - what does that prof do?
That's why it is a difficult problem. Cho was really obvious and the school blew his threat off.
Since prediction is a bear - we advocate that folks be allowed to carry on campus. However, that unleashes other issues.
1. Are students a peculiar risk if allowed to carry? Mature, immature, etc. There are older students vs. drunks in the dorms.
2. Carrying on campus - what are the responsibilities of the fac/staff carrier - are they pseudo-LEOs? This is an issue if the school explicitly allows carry as compared to it being a state law. The former implies an approved agency of the school rather than just being an armed citizen.
3. Training - this drives me wild. If you argue for carry on campus to specifically stop rampages - should you have a modicum of training for a high intensity gun fight and stress? I see posturing paper target and rock shooters want to carry on campus. Well, I think they should if state laws allow general CCW on campus. If they want special agency, as a guardian, then get your butt into training. If I were a cost / legal concerned administrator and you came to me and said - I want to carry, blah,blah, RKBA, blah, Blah - VT, Blah, blah - I might say back - well, how skilled are you? The reply, I shoot at rocks in the country. -- That will get you laughed at.
For me, the optimal solution is for state legislatures to null bans on carry on campuses (the great private property argument). The armed person on campus as no more responsibility than in the mall or church.
As for other comments - I repeat my position that I don't accept blanket rants that colleges are all - blah, blah, blah. All professors stink - blah, blah, blah. All Liberals - blah, blah, blah. Not productive and in fact, counterproductive if you want to make the RKBA case.
My sig article came out of a campus discussion about gun rights and the Pink Pistols on our school chat system. Then the NTI folks asked me to wirte it up. Harper's magazine had an article on why progressives should support gun rights - one major point was the fear of tyranny from the right.