How could anyone – let alone a 9-year-old – talk their way onto a flight without a reservation in the post-9/11 era? That’s what federal and airline officials have been scrambling to figure out since Semaj Booker made his improbable journey from Washington state to Texas.

Southwest Airlines was still looking into how the 80-pound, 4-foot-9 fourth-grader made his way through security and onto two flights Monday, from Seattle to Phoenix and then to San Antonio. Semaj, said to have been trying to reach his grandfather in Dallas, also is accused of leading police on a high-speed chase in a stolen car Sunday.

The TSA was working with Southwest to find out more details, said Jennifer Peppin, a spokeswoman for the agency.

She noted that the boy had a proper boarding pass, which is necessary to clear federal screening. How he came about getting that pass from Southwest was “their issue,” Peppin said.