The Post reports on the ongoing probe into the Virginia Tech shootings, with police reconstructing details of gunman Cho Seung-Hui's movements and searching for motives. Questions include whether Emily Hilscher, his first victim, was a random target, and the possibility that someone else mailed Cho's manifesto to NBC News.
The most salient mystery remains the two-hour gap between killings. Police speculate that Cho may have been foiled in the first assault by locked dorm rooms, or intended the early shootings to divert their attention from the later attack. Cops warn answers will be hard to come by; evidence from Norris Hall alone fills "a significant-sized trailer in a storage area."