The family of a teenager who authorities said hid in the wheel well of an airplane in North Carolina before falling from the sky over Milton has hired a Florida law firm to pursue legal claims in his death, the firm said yesterday.

The battered body of Delvonte Tisdale, 16, was found in a quiet subdivision in Milton in November. Milton police initially suggested that Tisdale was murdered, but former Norfolk district attorney William R. Keating said last month that Tisdale stowed away on a USAirways flight in Charlotte. The law firm representing the family believes lax security is to blame.

“The evidence in this case makes it quite clear which party is at fault, and the family has every intention of pursuing legal action of the highest order,’’ attorney Christopher Chestnut said in a statement.

“We intend to seek justice for a child who, although culpable for making irresponsible and immature decisions representative of his age, should never have successfully gained access to that airplane. Had airport security been up to par, he would be alive and well with his family today.’’

The Federal Aviation Administration and the Transportation Security Administration publicly committed to assisting in any investigation. The Charlotte airport is owned by the city and has also agreed to work with the federal agencies and municipal police to try and determine how Tisdale was able to evade security.

Ann Davis, a TSA spokeswoman, said yesterday that the agency could not comment because Tisdale’s relatives now have a lawyer and the agency does not comment on pending litigation. Davis referred to a TSA statement issued last month, saying the airport was responsible for keeping people out of secure airport areas.

In the statement, the Chestnut Firm, based in Gainesville, Fla., said the Tisdale incident raises questions about national security. Chestnut also said that the family had been asked by unidentified public officials to hold off announcing the launch of a civil investigation until air travel had ended for the Rev. Martin Luther King holiday.

“While we agreed with authorities’ request to hold off on announcing this case until after the busy holiday travel season to avoid inciting public outrage, panic, and possible logistical concerns during this critical period for the airline industry,’’ Chestnut said, “it’s now time this story be told and all facets of it explored — including the considerable ominous implications to our national security at large.’’ .

The mayor’s office in Charlotte referred questions about the city’s inquiry to the Charlotte-Mecklenburg Police Department. A call to the police public affairs unit was not returned yesterday.

John Ellement can be reached at ellement@globe.com.

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