Port Authority police found the body of a man believed to be in his 30s on British Airways Flight 177 after the plane landed at about 6:30 p.m. Tuesday, according to the Port Authority of New York and New Jersey.
The Queens District Attorney, federal Transportation Security Administration, FBI and city Medical Examiner's office were investigating.
British airways says it is investigating. And Heathrow's operator says it is willing to cooperate with police in New York and London, reports CBS News Correspondent Steve Holt, but there is no explanation for what could be a serious security breach.
It also is not known yet if the man got into the plane in London, or at an earlier stop.
Last week, the body of a man in his 20s was found in the wheel well of a flight to Kennedy Airport from Montego Bay, Jamaica.