ON THE morning of September 11, 2001, C. Lee Hanson received a call from his son, Peter, and was told that the plane he was on, United Flight 175, had been hijacked.

His son told him that a flight attendant had been stabbed to death, screaming passengers were vomiting, and his wife and 2½-year-old daughter, Christine Lee, were terrified. Peter said that he thought the hijackers were going to crash the plane into a building. Within seconds, the plane became the second airliner flown into the World Trade Centre.

“As we were talking he said, very softly: ‘Oh my God. Oh my God. Oh my God’. And there was a scream in the background.” Crying, Mr Hanson continued: “I looked at the television and saw the plane fly into the building.”

Mr Hanson, 73, was speaking at the trial of Zacarias Moussaoui, where the jury is hearing two days of searing accounts from victims’ relatives as prosecutors seek to convince the jury that the only person convicted in America over the September 11 attacks should be executed.

So graphic and upsetting was the testimony, which included the taped scream of one man as he spoke to an emergency dispatcher while the World Trade Centre collapsed, that the judge warned prosecutors not to overdo it.

The prejudicial impact of such heart-wrenching accounts can be so overwhelming, the judge said, that a death sentence could be overturned on appeal.

Several members of the jury broke down in tears as they heard descriptions of shattered lives and unbearable loss; stories of little boys who still wake at night calling for their dead fathers; of mothers sleeping in their dead daughters’ rooms.

Mr Hanson told how he had to retrieve DNA samples from hairbrushes and toothbrushes to help to identify his son, his wife, Sue Kim, and their daughter, the youngest of the nearly 3,000 people killed that day.

Months after the attacks Mr Hanson said that he had received a single bone from his son’s body, a few inches long. “I held the small bone in the palm of my hand,” Mr Hanson said. “It was all I had left of my beautiful son.”

For the first time two frantic emergency calls made by victims inside the World Trade Centre were played. Kevin Cosgrove, 46, a father of three working on the 105th floor of the South Tower, could be heard telling the emergency dispatcher: “Tell God to blow the wind toward the west . . . We’re very young. We’re not ready to die.”

Moments later, he says: “Please hurry. I’ve got young kids.”

As the jury watched scenes of the burning South Tower synchronised to the time of his call at 9.58am, they heard Mr Cosgrove yell: “Oh, my God . . . Ohhhh!” as the tower collapsed. The other audiotape captured the final minutes of Melissa Doi, trapped on the 83rd floor. She told the operator that she was with five others, lying on the floor of a smoke-filled room trying to breathe. She repeatedly said: “It’s so hot. It’s very, very hot. Please, God, it’s so hot, I am burning up.”

Then she said: “I am going to die, aren’t I? I am going to die.”

“No, no, no, no,” the operator said.

Sobbing on the witness stand, Mary Ellen Salamone said that she and her husband, John, a Cantor Fitzgerald broker on the 104th floor of the World Trade Centre, had been through ups and downs in their marriage. She said he died in the middle of a “not so good” phase.

She had called him “a million times” that morning but never got through. “I was so desperate to talk to him and tell him I loved him,” she said. “In death, I did not get John. I got a body bag seven months later that I had to say goodbye to in the basement of a refrigerated morgue, and I had to try and find peace with that.”

Ronald Hans Clifford described how he was tending to a terribly burnt woman in the lobby of the North Tower when the second plane hit. The woman died 41 days later. Mr Clifford would also learn that his sister, Ruth, and niece, Juliana, were on board the second hijacked jet.

Today the cockpit voice recording of passengers struggling to take control of United Airlines Flight 93 — which crashed into a Pennsylvania field — will be played in public for the first time.

Moussaoui pleaded guilty last year to conspiracy charges. He was in jail at the time of the attacks and jurors last month decided that his failure to tell the FBI about his knowledge of the plot cost at least one life.

Times Recommends

• UN may halt 400-year-old 'freedom of the seas'
• Where the Rosetta belongs can’t be set in stone
• Gas deal on hold, but Ukraine may pay in the end