Back story on bomb threats at VT

Here's the back story on the VT bomb threats in the last few weeks, apparantly the bomb threats did target the engineering school which is where a number of the shootings occured. I did not originally think the events would be correlated but it is odd the engineering school was repeatedly targeted.

http://abcnews.go.com/US/story?id=3045900&page=1

It will be interesting to see what the camera's on campus show. What was the shooter doing in the two hours between the dorm shootings and the engineering building shootings?