In 2004, TSA security officer Calhoun and his colleague Ganson were seen twice after Kate's escape at Los Angeles International Airport. They entered the elevator where Kate and Sawyer were traveling and Calhoun received a message about a code 341 on his two way radio. Shortly afterwards Calhoun was seen with a group of security officers and was shown what may have been a mug shot of Kate. ("LA X, Part 2")
Not credited, the name was heard in dialogue from Ganson's walkie-talkie.
TSA stands for Transportation Security Administration.