And it turns out that his mother works at the airport where he began his journey, the newspaper 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, according to the Star Tribune.
The newspaper reported that Moore said the boy's mother works at Minneapolis-St. Paul International Airport and that "there is also an investigation into whether she aided him flying to Las Vegas." The newspaper did not report who was conducting that investigation.
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.
The boy went through security with other passengers, the Transportation Security Administration said in a statement Sunday, but officials were still trying to figure out how he did it -- and how he then got on the flight Thursday.
Patrick Hogan, a spokesman for the airport, said the crew "became suspicious of the child's circumstances" during the flight. Crew members got in touch with authorities in Las Vegas and turned the boy over to Child Protective Services, Hogan said in a statement.
The boy's status was to be discussed in a Las Vegas court Tuesday, a spokesman for Minnesota's Hennepin County said. He remained there pending a decision on what to do with him.
The agency did not immediately return a CNN telephone message Tuesday seeking comment on the Star Tribune report.
According to the Star Tribune, Moore said child protective workers have investigated the boy's family life four times.
"The reports have been inconsistent and there have been no injuries to the child; however, there is a pattern of behavior," the newspaper quoted her as saying in the e-mail.
The newspaper said Moore wrote that the boy was arrested two weeks ago after allegedly stealing a car. The e-mail didn't indicate whether the boy was the driver of the car or a passenger, the newspaper reported.
The newspaper also said Moore wrote that the boy has alleged that his mother has held a knife to his throat and that she was "stabbed and died."
"Typically, staff can tell if a child is lying, but with this child, they are unsure what is going on," the newspaper quoted the e-mail as reading.