The investigation into the crash of the EgyptAir jetliner with the loss of 217 lives is now focusing on the actions of a co-pilot whose last words have been heard on the recovered voice recorder.
According to officials, the copilot, Mr Gamil al-Batouti, was alone in the cockpit when he is heard saying "I made my decision now. I put my faith in God's hands." Immediately after this, the autopilot was turned off and the Boeing 767 began a steep dive from 33,000 feet.
According to sources who have spoken to Associated Press, the chief pilot, Mr Ahmed alHabashi, then returned to the cockpit and his voice can be heard saying "Pull with me. Help me. Pull with me." Officials have also said that there may have been sounds of a struggle on the audio-tape.
Later, the two jet engines were turned off and the plane climbed for a brief period before breaking up and falling into the Atlantic Ocean in international waters off Nantucket Island, Massachusetts.
US officials are studying why Mr Batouti was flying the plane so soon after leaving New York as he was a relief co-pilot apparently meant to take over much later during the 11-hour flight to Cairo.
It is the evidence on the voice recorder that has led to the decision by the National Transportation Safety Board in Washington to turn over the lead role in the investigation to the FBI, which had already been assisting the NTSB.
But the Egyptian government and EgyptAir have objected to the FBI taking over and making it a criminal investigation until Egyptian officials have studied the voice recorder.
The chairman of the NTSB, Mr James Hall, said that there were "significant differences in the cultural interpretations of some expressions on the recorder." This was why he had decided to wait for the Egyptian officials to study the tape further.
There has been strong reaction in Cairo from relatives and the media at the suggestions in the US press that a suicidal Mr Batouti deliberately pushed the plane into a fatal dive.
There have been reports that he had sent savings back to his family before his last flight and that he may have been depressed at his impending retirement next March when he would reach the age of 60.
Mr Batouti also had a 10-year-old daughter, Aya, who has a serious disease of the immune system requiring regular treatment in the US.
Mr Batouti's apartment in Cairo is now being guarded by an armed policeman to keep the media away.
His son, Mohammed, has denied reports that his father had sent his life savings home because he planned suicide. The son told the newspaper, al-Ahram, that he spoke with his father in the US two days before the crash and asked him to send $300 home with a friend to pay a telephone bill and this is what he did.
Mr Batouti, who has five children, had spent more than 35 years in aviation, amassing 14,300 flight hours. He joined EgyptAir in 1987 and before that had trained pilots in the air force and in civil aviation.
The New York Times yesterday reported the concierge at the Manhattan apartment building where Mr Batouti stayed when in New York as saying that he was "a little depressed" because he had not been made a captain.
But Mr Batouti's wife, Ms Umayma al-Dahi, told the al- Gomhuria newspaper that she could not believe he would commit suicide. He had told her hours before the fatal flight that he had hopes their daughter would be cured of her disease and that he would be taking her again to California for treatment.
She said that her husband had also promised to take all the family on a pilgrimage to Mecca after the flight.
The head of Egypt's civil aviation authority, Gen Abdel Fatah Qatus, has travelled to Washington at the head of a delegation of techical experts and security and military intelligence officers. Some 33 Egyptian military officers were on Flight 990, some of them intelligence officers returning from training courses.
There was outrage in Cairo at the claim that the Islamic prayer, el shahada, was a prelude to suicide and mass murder.
Mr Ali Murad, secretary general of the Egyptian Pilots' Association and an EgyptAir official, said that it would be normal for the pilot to have recited the shahada, "because this is what all Muslims do when they face a death situation".