A 9-year-old boy who evaded airport security and stowed away on a flight from Minneapolis to Las Vegas has also stolen a car and sneaked into a water park, and he is known to child protection investigators, according to a confidential county government memo.

In the email, Janine Moore, area director of the Hennepin County Human Services and Public Health Department, said child protection staffers have conducted four assessments of the boy’s family since December and that he is a “challenging” child.

“The reports have been inconsistent and there have been no injuries to the child; however, there is a pattern of behavior,” she wrote in the email to county administrators and commissioners marked “private data.”

When reached by the media Tuesday, Moore said she couldn’t comment. “That information went out without my authorization, so there’s nothing more I can share with you about that memo,” she said.

Hennepin County spokeswoman Carolyn Marinan said the memo is considered private under state law. She said she couldn’t disclose any other details about the county’s involvement except to say the boy is safe.

The memo did not identify the boy or his family or say where they live.

The email did say, however, that the boy’s mother works at Minneapolis-St. Paul International Airport, where he sneaked onto the plane without a boarding pass or identification Thursday. The Delta Air Lines flight crew realized mid-flight that he wasn’t supposed to be there, and Las Vegas authorities took him into custody when the plane landed.

The boy became “violent” and was hospitalized in Las Vegas, where hospital staff reported he was “uncontrollable” at first but eventually calmed down, it said.

Minneapolis airport spokesman Pat Hogan said he got through the security checkpoint at least in part by blending in with another family. According to Moore’s memo, that’s also how he sneaked into the water park.

His motivation for the trip remained unconfirmed.

“What he told the police in Las Vegas was that he was going to meet a kid he had met online who shared his interest in video games,” Hogan said. “His mother also said they didn’t have any family or friends there so I don’t know if that’s true or not, but that’s what he told authorities in Las Vegas.”

A hearing in Las Vegas about the boy’s case has been scheduled, said Chuck Laszewski, spokesman for Hennepin County Attorney Mike Freeman. The child protection division in the county attorney’s office will also investigate but was waiting for officials in Las Vegas to wrap up their work, he said.

The boy is too young to be charged with a crime, officials say.

The airport police department would not release its reports on the incident Tuesday. While the federal Transportation Security Administration finished reviewing them, local officials were still determining whether they could release the reports because they concern a juvenile.

In addition to detailing his history of sneaking into a local water park, the memo said the boy drove a stolen vehicle down Interstate 35. Police haven’t said whether he’s the same 9-year-old boy who stole a delivery truck in Minneapolis on Oct. 1 — two days before the airport incident — drove down I-35 and eventually crashed into a stationary suburban Edina Police Department squad car on a city street. The crash caused $5,888 in damage to the squad car, but nobody was injured.

Martin said she didn’t know if it was the same boy, while Minneapolis police spokesman Sgt. William Palmer said state law prohibited him from confirming or denying it.