Seung-Hui Cho, who committed the Virginia Tech massacre in 2007, had been diagnosed with severe anxiety disorder as a child and placed under treatment.
But Virginia Tech was prohibited from being told about Cho's mental health problems because of federal privacy laws.
At college, Cho engaged in behavior even more bizarre than the average college student. He stalked three women and, at one point, went totally silent, refusing to speak even to his roommates. He was involuntarily committed to a mental institution for one night and then unaccountably unleashed on the public, whereupon he proceeded to engage in the deadliest mass shooting by an individual in U.S. history.
The 2011 Tucson, Ariz., shopping mall shooter, Jared Loughner, was so obviously disturbed that if he'd stayed in Pima Community College long enough to make the yearbook, he would have been named "Most Likely to Commit Mass Murder."
After Loughner got a tattoo, the artist, Carl Grace, remarked: "That's a weird dude. That's a Columbine candidate."
One of Loughner's teachers, Ben McGahee, filed numerous complaints against him, hoping to have him removed from class. "When I turned my back to write on the board," McGahee said, "I would always turn back quickly -- to see if he had a gun."
On her first day at school, student Lynda Sorensen emailed her friends about Loughner: "We do have one student in the class who was disruptive today, I'm not certain yet if he was on drugs (as one person surmised) or disturbed. He scares me a bit. The teacher tried to throw him out and he refused to go, so I talked to the teacher afterward. Hopefully he will be out of class very soon, and not come back with an automatic weapon."
The last of several emails Sorensen sent about Loughner said: "We have a mentally unstable person in the class that scares the living cr** out of me. He is one of those whose picture you see on the news, after he has come into class with an automatic weapon. Everyone interviewed would say, Yeah, he was in my math class and he was really weird."
That was the summer before Loughner killed six people at the Tucson shopping mall, including a federal judge and a 9 year-old girl, and critically wounded Rep. Gabrielle Giffords, among others.
Loughner also had run-ins with the law, including one charge for possessing drug paraphernalia -- a lethal combination with mental illness. He was eventually asked to leave college on mental health grounds, released on the public without warning.