Professors had become alarmed at his disturbing writings and his demeanor. From one class he was expelled, and counseling was recommended but could not be forced.
To others the signs were less obvious. Suitemates and acquaintenances described him as a loner, one who never spoke or looked them in the eye. They thought it odd, but were surprised at the level of the hatred that was simmering.
Behind their backs, perhaps in the very rooms where they co-existed, Cho was typing out a manifesto, railing against the rich and spewing illogical, sick rhetoric. He was taping video messages and snapping digital photos through which we now see and hear and read that hatred.
In classes, he wrote troubling plays and used a question mark when asked to put his name on a list. He reportedly took cell phone photos of female students from under his desk.
In the snippets of video released last week by NBC, to which Cho mailed his work on a stop between one shooting and another, our subconscious sees again the faces of Dylan Kleebold and Eric Harris, the two teens who killed classmates in 1999 at Columbine High School in Colorado.
We see as well the images of suicide bombers in the Middle East who have recorded defiant messages to be shown after their acts of murder and suicide, declaring their targets to be at fault, declaring themselves as martyrs.
We are not surprised, then, to learn that Cho has made reference, directly or indirectly, to his heroes from both of these venues.
He builds his own martyrdom: "You have vandalized my heart, raped my soul and torched my conscience â?¦ You thought it was one pathetic boy's life you were extinguishing. Thanks to you, I die like Jesus Christ, to inspire generations of the weak and the defenseless people."
The comparison to Christ is, of course, the most revealing example of the twisted logic used by Cho to justify his feelings, and ultimately his rampage.
How does our society identify such danger building but remain unable to stop it in its tracks?
Some will say it is our freedom of movement combined with our growing demand for individual privacy (Cho chose not to be treated, and his diagnosis remained secret). Some point to our fascination for violence in art and entertainment and its distribution to the very young. Some say it is our tolerance for guns and their limited regulation.
But freedom does not translate into evil, as much as our enemies would like the world to come to that conclusion. Art, even bad art, does not provide a negative influence unless its interpretation is unsupervised. And guns are but a substitute for other weapons just as lethal.
Somewhere along the way Dylan and Eric and Cho and others with violence and death as their solution lost a lust for life, a love for their fellow man, and perhaps an understanding of the real reason Christ died.
It is to that point in their lives we must go to find solutions for others so possessed. Everything else is just the treatment of a symptom.