The Virginia State police expect to close the two crime scenes at Virginia Tech as soon as Thursday, having collected all the evidence they can in the wake of Monday's shooting rampage that left 33 dead.
State, local and federal law enforcement officers have banded together to do hundreds of interviews and sift through mounds of physical and forensic evidence. They are hoping to piece together a seamless narrative that will provide some insight into why 23-year-old Seung-hui Cho decided to open fire on his fellow students.
Officials have been careful not to reveal too much information about what they have discovered at the crime scenes. On Wednesday, they had thought the discovery of Cho's multimedia manifesto would provide a big break in the case. But in Blacksburg, Va., on Thursday, Virginia State Police Superintendent Steven Flaherty seemed to be focusing on anything that might lead investigators to a motive.
"We're hoping any evidence we recover will give us some information that leads us to the bottom line to building a case that answers what and — as much as possible — why," Flaherty told reporters at a press conference on Thursday.
Law enforcement sources told NPR that they are still searching for a connection between Cho and the students he shot. They don't know whether Cho was looking for anyone in particular as he went from classroom to classroom reloading guns and taking aim at the students. And while two of the victims graduated from Cho's high school, it isn't clear whether he even knew them.
NPR has also learned that investigators have some leads related to a trail of bloody footprints in the hallway of West Ambler Johnston dormitory where the first two killings took place. The police had been trying to connect Cho to that crime scene, but no one seems to have seen him in that dorm on Monday morning. A matching shoe print could place him there.
The problem is that shoe comparisons can take some time to nail down. If police can't get a clear match from a footprint, they will have to turn to DNA, and that could be problematic if Cho stepped in other blood during the second shooting in Norris Hall. Police have declined to comment on that part of the investigation.
NPR asked Flaherty today about the footprints and he said he would not "respond to that."
Investigation hope to wrap up the how of this case in the next few days and then turn to the question everyone is asking: Why?