(CNN) -- Authorities are investigating what happened to a North Carolina teenager whose body was found along a flight path in Massachusetts with "trauma that was consistent with a fall from a significant height," a Massachusetts district attorney said.
"It appears, more likely than not, that (Delvonte) Tisdale was able to breach airport security and hide in the wheel well of a commercial jetliner without being detected by airport security personnel," William R. Keating, district attorney for Norfolk County, Massachusetts, told reporters Friday.
The mystery started November 15, when 16-year-old Delvonte was last seen by a sibling at their home in Charlotte, North Carolina, according to Keating.
Later that day, his family discovered Delvonte wasn't home and reported him missing.
"About 7 p.m., a Boeing 737-400 aircraft was boarded and took off from North Carolina's Charlotte Douglas International Airport, en route to Boston's Logan Airport," Keating told reporters.
"At approximately 9:30 p.m. that same evening, a group of area college students came upon a severely injured body" in the town of Milton, Keating said. "This was directly below a flight path."
The body was later determined to be Delvonte's.
The autopsy on Delvonte's body "did not reveal any knife or gun wounds, but did show trauma that was consistent with a fall from a significant height," Keating said. He said a toxicology test turned out negative.
Investigators examined two planes that had originated in Charlotte and followed a similar flight path, Keating said. They found "what appeared to be physical evidence of someone having been in a left wheel well of one of the planes was located and documented -- including hand prints visible in greasy areas and scuff marks in the area that would accommodate a person."
On Friday, Milton police and other authorities conducted a search of the wooded area along the flight path, Keating said.
"They recovered two dark Nike Air Force sneakers with white stripes, consistent with those that the Tisdale family describe as belonging to Delvonte," Keating said.
During the investigation, Keating said, one local resident described hearing a loud, crashing noise shortly before 9 p.m. the night Delvonte's body was found.
State police have ruled out motor vehicle homicide as a possible cause for Delvonte's injuries.
"The theory that the death may have involved a fall from a passing airplane -- as has happened in other parts of the country and other parts of the world -- began to be explored," Keating said.
Fingerprints lifted from Delvonte's body were run through a national database, but no matches were found.
"But investigators released a handwritten note found in the pocket of the jeans he was wearing, and a member of the family recognized the name and made contact with Milton police," Keating said.
Last week, Massachusetts state and local police traveled to North Carolina to take samples of grease used in maintaining aircraft to see if the grease found on Delvonte's pants could be matched to that grease, Keating said. Forensics tests are still pending.