The idea of a second Virginia Tech gunman was initially supported by police investigators, however it was abruptly dropped shortly after the massacre.
However there are a number of events and circumstances that indicate the presence of a second gunman.
Park Chang-Min, a 27-year-old engineering student at Virginia tech, said in an interview with South Korean journalists that the perpetrator "... hid his face behind a mask and had his brown-coloured cap lowered to his eyes. He wore glasses and something like a black ammo jacket". This information conflicts with another eye-witness report that claims Cho was dressed "almost like a Boy Scout".
Furthermore a report released by Fox News states that "A government official with knowledge of the shooting said the gunman had been arrested."
Officials also persued Karl Thornhill as a suspect of the first shooting while the larger massacre took place. At 8:25am on Monday the 16th of April Police detained Karl Thornhill for questioning.
Another reason for believing there was a second gunman is the accuracy of the killings. A fire arms instructor recently said that most people, unless heavily trained and highly skilled, lack competence in the use of fire arms.
An example of this is in an LA police shooting. A Police Officer fired 112 rounds from close range but nicked the suspect only once. The suspect was not engaging the Officer. The Officer was presumably well trained in the use of fire arms and yet he could only exact minimal damage upon the potentially dangerous suspect.
How could an untrained college student show more proficiency in fire arm use than a well trained LA Cop?
Such proficiency can only come from extended periods of practice. This is not the work of an amateur.
Was Cho Seung-Hui assisted by a trained, masked assassin?
(More updates as they come.)