From BBCCho Seung-hui [wiki]was a deeply disturbed young man - as the shocking and horrifying video he left behind reveals.
It appears that the 23-year-old's actions and intentions fell into a pattern of previous school and college shootings.
Robin Kowalski, a psychologist at Clemson University in South Carolina, has co-written a comprehensive study on school shootings. She told the BBC News website that Cho's actions bore strong similarities with other killings.
Like Eric Harris and Dylan Klebold - perpetrators of the Columbine massacre - and Kimveer Gill, who went on a killing spree at a Canadian school last year, the foundation for Cho's violent act was laid out long before it took place.
And, like those killers, he left behind rage-filled testaments - Harris, Klebold and Kimveer via the internet, Cho via his video.
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