The TECS as in "TECS stop" is an acronym which refers to the updated and modified version of the former Treasury Enforcement Communications System. It is used by Customs and Border officials to screen individuals who seek to enter the country. TECS allows access to a Federal database, a one-stop shop, maintained by multiple agencies which allows uploads from their own agents as well.
The team of John Allen Muhammad and Lee Boyd Malvo, were collectively known as the "DC Sniper". Muhammad was the mastermind who instructed his one-time girl-friend's son Malvo to shoot random people from the trunk of his car in the DC metropolitan area in October 2002. The end-game of these shootings was to create a pretext that would deflect blame from Muhammad when he eventually had his wife killed, as he hoped the murder would be interpreted as a random act of violence attributable to the DC Sniper.
Seung-Hui Cho, who is referred to as the Virginia Tech shooter, was a South Korean national but was raised in the United States. He went on a killing spree on April 16, 2007, to settle unspecified grievances.