A woman's scream of "I don't want to die, I don't want to die," crashes, shouts, and the sounds of fighting echoed through the tense Virginia courtroom, as the cockpit voice recorder of United Airlines flight 93 was played in public for the first time.
Moussaoui is facing execution or life in prison without parole. He grinned broadly as the gruesome 31-minute tape transfixed jurors, lawyers and observers.
Three planes had already smashed into the World Trade Center on that fateful 2001 day, and passengers vowed in phone calls to relatives from the plane that they would try to seize back their jet before it reached its target.
In the final seconds before the plane turned almost on its back and went into a deep dive and crashed in a Pennsylvania field, a voice is repeatedly heard saying "Allah is the greatest, Allah is the greatest" in Arabic.
Seconds earlier, there were clear signs of a struggle, presumably between hijackers and passengers who had told relatives in mobile phone calls that they were planning to seize back the jet.
Amid bangs, crashes and groans seemingly from outside the cockpit door, a voice in Arabic says "hold from the inside, hold from the inside," as hijackers apparently try to ward them off the revolt.
A minute later, there is another Arabic exchange. "Shall we finish it off? No, not yet.... when they all come, we finish it off."
Rocking wings
The pilot hijacker, presumed to be Ziad Jarrah, then starts rocking the wings violently from side to side, a movement shown to jurors on a simultaneous computer depiction from the flight data recorder, which was also recovered from the crash site.
A voice in English is heard saying "Let's get them," following by the sounds of commotion as passengers apparently try to break into the cockpit.
As the plane pitches violently and loses altitude, descending to around 2,120 metres (7,000 feet), a voice is heard saying in English "In the cockpit. If we don't, we'll die" followed by the words "Roll it."
A hijacker asks again in Arabic "shall we put it down" as crashing sounds are heard and shouts in English of "Go, go, move, move."
A hijacker then says in Arabic "Put it down" while the words "Push, push, push" are heard in English.
Seconds later, a voice in Arabic says "Allah is greatest!" three times, as a voice in English shouts "No."
Then the tape cut off off abruptly, leaving silence in the courtroom, along with the realisation that the plane had crashed, killing 33 passengers, seven crew members and four hijackers.
Minutes after playing the tape, prosecutors called Lorne Lyles, husband of United Flight 93 flight attendant CeeCee Lyles to the witness box.
As he choked back tears, prosecutors played a telephone message CeeCee left for him minutes before the plane crashed, and which he discovered a week after her death.
"Hi baby, you got to listen to me very carefully," Lyles was heard saying.
"I am on a plane that has been hijacked, I want you to know, I love you. Please tell my children, I love them very much. I heard that there have been planes thrown at the World Trade Center. I hope to be able to see your face again baby, I love you. Bye. Bye."
Prosecutors ended their case by showing the jury a large mosaic, filled with small pictures of all but 92 of the nearly 3,000 victims of the September 11 attacks.
"The United States of America rests," prosecutor David Novak told Judge Leonie Brinkema, ending four days of harrowing testimony of the horror the World Trade Centre and the Pentagon, and the agony of families left behind.
Defence lawyers are due to open their case on Thursday, and are expected to argue that Moussaoui is mentally ill and therefore should not be put to death.
Moussaoui, a Frenchman of Moroccan descent, who the jury has already judged eligible for execution, has the right to testify in his own defence – an option he is sure to take, over the opposition of his lawyers. He could take the stand as early as Thursday.
Death linked to 9/11
Meanwhile, a New York policeman's death has been linked to work at ground zero. A US coroner's made the first known ruling linking a death to recovery work after the 9/11 destruction on the World Trade Centre site.
New Jersey coroner James Zadroga says the death of a 34-year-old police detective who developed respiratory disease after working at ground zero was directly related to the collapse of the twin towers which were hit by hijacked planes in 2001.
A class action lawsuit and families of ground zero workers have alleged that more than two dozen deaths are related to exposure to toxic trade centre dust and tower debris.