The Transportation Security Administration on Tuesday closed its investigation into an incident involving Sen. David Vitter, finding that the Louisiana Republican did not pose a security threat when he set off an alarm at Dulles International Airport on March 5. Roll Call first reported that Vitter lost his temper when he arrived at his gate and found that the door had been closed. the GOP Senator opened the door, set off the alarm and had a subsequent confrontation with an airline worker, a witness said.TSA said Vitter “caused a door to alarm but did not proceed into a restricted area,— and noted that its review of the incident was complete.