SEATTLE (AP) – 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 on Sunday.

“This is such an unusual situation, there’s a lot of facets to it that we’re looking into,” airline spokeswoman Marilee McInnis said Friday.

U.S. Rep. Norm Dicks, D-Wash., has asked the Transportation Security Administration to determine how the boy got another passenger’s name to get on board.

“As Norm says, we spend billions of dollars inconveniencing the American public and making things safe – we think,” Dicks’ spokesman George Behan. “Then a 9-year-old comes walking through.”

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.

In a statement Wednesday, Southwest said the boy was issued a boarding pass at Seattle-Tacoma International Airport after he gave information matching a reservation and told workers his mother was already in the boarding area.

On Friday, Semaj was being held at a center for runaways in Bexar County, which includes San Antonio. Semaj was stopped by Southwest employees at the airport there when he tried to board a Dallas-bound flight.

The boy probably will remain at the center until his grandfather or another guardian can take custody of him, said Fred Wist, a prosecutor in Washington state’s Pierce County.

Wist has filed charges against Semaj in connection with Sunday’s high-speed pursuit. Authorities say Semaj, who had run away before, eluded police at speeds of 80-90 mph until he took an exit and the engine blew. He was returned home but ran away again Monday.

Semaj’s mother, Sakinah Booker, 29, has said her son dislikes the Lakewood neighborhood where the family lives and is afraid of a sex offender who lives nearby. Wist said Friday that investigators confirmed a sex offender was living in the area, but there had been no reports of any contact with the child.

Calls to Booker’s home rang unanswered Thursday and Friday.

She has retained Tacoma lawyer Brett Purtzer, who did not return several messages seeking comment.

Wist said it’s too early to say whether his office will proceed with charges if Semaj is returned to Washington state.