Jury members listened to the "voices of victims" into the courtroom, with prosecutors hoping to convince jurors Moussaoui should die for concealing the planned attacks in August 2001.
Jurors heard the terrifying final phone call to an emergency dispatcher by Kevin Cosgrove, who was working on the 99th floor of the south tower of the World Trade Centre on September 11, 2001.
The final snippet of conversation coincided with the moment at 9.58am when the tower collapsed in a vast cloud of smoke, flame and debris.
Meanwhile grandfather C Lee Hanson told the Virginia court how his son Peter, daughter-in-law Soo-Kim, and two-and-half-year-old granddaughter Christine Lee Hanson, were on a plane en route for Disneyland on September 11.
“I think they are going to try to crash this plane into a building," Mr Hanson, quoted his son as telling him in a cell phone call from the hijacked plane.
"He said: 'Don't worry Dad. If it happens, it will be quick'," he continued.
"As we were talking, all of a sudden he stopped and said very softly: 'Oh my God, oh my God, oh my God'."
"I looked over at the television set and saw a plane fly into the building," Mr Hanson said, describing how the hijacked jet rammed into the World Trade Centre in New York.
A phone conversation between 34-year-old Melissa Doi and emergency services was also played.
Ms Doi was on the 83rd floor of one of the twin towers before it collapsed.
"The floor is completely engulfed, it is very, very hot. I am going to die aren't I? I am going to die, I am going to die," Ms Doi could be heard screaming.
"Please God, it is so hot, I am burning up."
Eligible for the death penalty
Moussaoui shouted "Hollywood, Deadly Circus!," as the court broke up for lunch.
Several times he seemed to be smiling at the harrowing testimony, and added at the end of the day: "God curse you all, God bless Osama."
He has previously told the court he would have flown a plane into the White House on September 11 but was arrested weeks before.
The jury has already ruled that Moussaoui is eligible for the death penalty, finding his deception prevented any chance to avoid the attacks and that he contributed to the almost 3,000 deaths.
Now they are hearing testimony on the impact of the crimes as they decide whether he should be put to death. The trial continues on Tuesday.