The apparent ease with which the boy, who is from Minneapolis, was able to get through security and onto a flight on Thursday raised questions about airport and airline security.
The boy is the son of a woman who works at the airport and county child-protection staff have reviewed his family situation four times since December, according to an email from Janine Moore, area director of Hennepin County's Human Services and Public Health Department, which was obtained by the Minneapolis Star-Tribune newspaper.
Moore could not immediately be reached by Reuters on Tuesday for comment on the email, which the newspaper said was written on Monday and sent marked as private to county administrators and board members. Moore's email did not identify the boy.
The boy was able to get through security at the airport on Thursday morning without a boarding pass and get on a Delta Air Lines flight to Las Vegas. His status was not discovered by flight crew until the airplane was in flight, authorities say.
Las Vegas police took the boy into custody when the airplane landed and the incident is under review by the Transportation Security Administration and Delta.
The boy rode to the airport Wednesday on the light rail system that runs from downtown, took a bag from a luggage carousel and went to an airport restaurant where he ate and then left the bag and an unpaid check, said Patrick Hogan, a spokesman from the Minneapolis-St. Paul airport.
Hogan said the boy would not face charges on the incidents because of his age.
According to Moore's email, the boy had a history of taking the light rail without his parents to a suburb near the airport, where he would blend in with a large family to get into a water park.
Moore wrote in the email that the boy stole a car two weeks ago and was arrested on a highway, the newspaper said. The newspaper says her email does not mention where he was arrested or whether he was driving at the time.
(Reporting by David Bailey; Editing by Greg McCune and Nick Zieminski)