READ: Boy Who Sneaked Onto Airline Flight

A flight to America's adult playground, Las Vegas, had an unusual passenger last week: a 9-year-old boy traveling on his own, apparently without a ticket.

The boy went through security with all other passengers, the Transportation Security Administration said in a statement, but officials are still trying to figure out how he did it -- and how he then got on the flight.

Patrick Hogan, a spokesman for Minneapolis-St. Paul International Airport, said the crew of Delta Flight 1651 "became suspicious of the child's circumstances" during the flight from Minneapolis to Las Vegas. Crew members got

in touch with authorities in Las Vegas and turned the boy over to Child Protective Services, Hogan said in a statement.

"Fortunately, the flight crew took appropriate actions to ensure the child's safety, so the story does have a good ending," he said.

Delta said it takes the incident "very seriously" and is working with authorities.

The airline spells out its policy about children flying solo plainly on its website.

Children between the ages of 5 and 14 may travel alone as part of the unaccompanied minor program. Someone from Delta pays special attention to the children, walks them on board, shows them their seats and even introduces them to the cockpit crew, time permitting, Delta says, adding, "Kids love this part.

 This 9 year old boy who hopped a flight to Las Vegas is no stranger to child protection investigators, who say he has a history of sneaking into a water park and was recently arrested after allegedly stealing a car, according to an e-mail obtained by the Minneapolis Star Tribune.

And it turns out that his mother works at the airport where he began his journey, a source close 

 to the situation said. The newspaper reported that Janine Moore, area director of the Hennepin County Human Services and Public Health Department, wrote in an e-mail to agency administrators and County Board members of the boy's "pattern of behavior," which has included hanging out at a Bloomington, Minnesota, water park and blending in with a large family to slip through without paying.

She describes him as a "challenging" child

However, authorities have been trying to figure out how the child was able to slip past security and airline gate agents and board Delta Flight 1651 without detection