ABC News reported Thursday that the FBI is "weighing" criminal charges against the brothers. The brothers' names haven't been released, but they had nearly identical names, according to ABC News' law enforcement sources. They are also American citizens.
The brothers were both going to Tokyo late Tuesday night from LAX to Tokyo and boarded an All Nippon Airways (ANA) flight. However, one of the brothers was booked on a United Airlines flight.
ABC News' sources say the two carried print-outs of the same ticket and were still able to board. The brother with a United ticket also found a seat on the ANA plane.
The flight crew didn't realize the mistake until the plane was already in the air for four hours. The pilot turned the plane back and landed at LAX, where the brothers were interviewed and released.
"During the flight, the cabin crew became aware that one of the passengers boarded the incorrect flight and notified the pilot. As part of the airline’s security procedure, the pilot in command decided to return to the originating airport, where the passenger was disembarked," ANA said in a statement.
The airline is "researching the situation currently to determine how the passenger boarded the flight."
The flight gained international attention as supermodel Teigen live-tweeted the ordeal to her 9.2 million followers. She didn't get back on a flight to Tokyo until early Wednesday morning, and arrived in Tokyo later that day.
"Honestly everyone on the ground and in the air were very kind and apologetic," Teigen wrote. "But I just need to know why we couldn’t have flown to Tokyo and settled this one person’s mistake (who was going to Tokyo all along) there, in Tokyo. 230 people on this flight."
Honestly everyone on the ground and in the air were very kind and apologetic. But I just need to know why we couldn’t have flown to tokyo and settled this one person’s mistake (who was going to tokyo all along) there, in tokyo. 230 people on this flight. https://t.co/EhCTERTRu5— christine teigen (@chrissyteigen) December 27, 2017
ABC News' sources said the brothers haven't been charged yet because the investigation is ongoing.