ASHINGTON, July 29 — An assistant United States attorney told relatives of people who died on United Flight 93, the hijacked jet that crashed in western Pennsylvania on Sept. 11, that he believed that the passengers had broken down the cockpit door with a food cart, a book being published on Tuesday says.
The prosecutor gave his interpretation three months ago at a hotel in Princeton, N.J., where the F.B.I. had gathered the families to listen to the cockpit voice recorder, said family members at the event who were interviewed for the book, "Among the Heroes" (HarperCollins).
But the prosecutor and other law enforcement officials have refused to talk about the contents of the recording because, they say, it could be used as evidence in a trial. The assistant United States attorney quoted in the book by family members, who are not identified, is David J. Novak, a lead prosecutor in the case of Zacarias Moussaoui, the Frenchman who has been called the 20th hijacker.
Law enforcement officials said today that the situation described by Mr. Novak was one of the theories of what happened in the final minutes of the flight. But the officials said that the words and sounds in the recording were not definitive.
The passengers on Flight 93, a Boeing 757 from Newark bound for San Francisco, had made clear in telephone calls to relatives and friends on the ground that they intended to storm the cockpit. But whether they followed through on those intentions or recaptured the aircraft has not been publicly confirmed. If Mr. Novak told the relatives that the passengers had entered the cockpit, that would appear to be the most detailed characterization of the events by a government official to a broad audience.
The new book, by Jere Longman, a reporter for The New York Times, is a minute-by-minute account of the flight and a biography of people on the plane. In an epilogue, it reports the recollections and notes of some of the approximately 70 relatives who gathered to hear the tape, which was accompanied by a transcript projected on a video screen.
According to the book: "At 9:58, the final battle for control of the plane began. The passengers were coming, trying to get into the cockpit, the hijackers said, admonishing each other to hold the door. `In the cockpit, the cockpit,' was shouted in English. A thumping sound could be heard."
The account continues: "A male voice screamed, perhaps as one of the hijackers was overtaken. `Hold!' was screamed in English. To some, it sounded as if the passengers were saying this in unison. `Stop him,' someone shouted. `Let's get them,' one of the passengers yelled.
" `If they didn't do this,' one passenger said in garbled words, `we'll die.' "
According to Mr. Longman's account, the hijackers could be heard praying, "God is great," and one of the terrorists urged that the air supply to the cabin be turned off. (At the plane's low altitude, this would not have mattered.)
"One of the hijackers spoke about finishing off the flight," according to the book. "Not yet, another terrorist cautioned."
The book goes on: "Near the end of the tape, muted voices seemed to grow louder, closer. The scuffling continued. `I'm injured,' someone said in English. More shouting: `Roll it' and `Pull it up' or `Lift it up' or `Turn up.' A final rushing sound could be heard, and about three minutes after 10, the tape went silent."
The plane carried 37 passengers, including four hijackers; five flight attendants; and two pilots.