On April 22, 2008, almost exactly one year after 32 students and faculty members were slain in the massacre at Virginia Tech, the dealer who had sold one of the weapons used by the gunman delivered a public lecture on the school’s campus. His point: that people at Virginia Tech should be allowed to carry concealed weapons on campus.

Eric Thompson, owner of the online firearms store that sold a .22-caliber semiautomatic handgun to the shooter, Seung-Hui Cho, did not think that his appearance at Virginia Tech was disrespectful or that his position was extreme. He felt so strongly that college students should be allowed to be armed while engaged in their campus activities that he offered discounts to any students who wanted to buy guns from him.

Thompson spun the discounts as altruistic. He told ABCNews.com, “This offers students and people who might not have otherwise been able to afford a weapon to purchase one at a hefty discount and at a significant expense to myself.”

The sale to Cho was not Thompson’s only unfortunate link to a mass killer. His firm sold a pair of 9-millimeter Glock magazines and a holster to Steven Kazmierczak, a 27-year-old graduate student in DeKalb, Ill., who, on the afternoon of Feb. 14, 2008, went heavily armed into an auditorium-type lecture hall at Northern Illinois University. Kazmierczak walked onto the stage in front of a crowd of students and opened fire. He killed five people and wounded 18 others before killing himself.