Cho Seung Hui actually sent a package, time stamped 9:01 a.m. to NBC news during a small break during his massacre. The package included photographs of himself holding and pretending to slice the air with the weapons used in the deadly affair. Along with the photographs were writings (English Major) that he'd wrote about the even that was about to occur.
It appears that he was trying to show them that he was some hero, ending his own life for the sake of building up his own army. An army of defenseless people as he put it. The people have discovered (due to his package) that he was stalking several female college students.
This package was actually mailed between the first shooting and before the second one. Which could be one reason why he wasn't caught at the time. The police are currently looking into the name, "Ismail ax" which was written in red ink on his arm and on the package sent to the news.
In the end, Cho would kill 32 innocent people before ending his own life.