Friends of an Egyptian billionaire who fell four floors to his death are adamant that he did not commit suicide.

Ashraf Marwan, son-in-law of the late President Nasser, was found dead outside his flat in St James’s Park, Central London, on Wednesday. He had been fearing for his life after he was named as a spy for Israel, an allegation he denied.

Police have not found a suicide note and are treating his death as “unexplained”. Investigators are exploring three possibilities – that he was murdered, that he jumped or that he accidentally fell.

Friends and relatives of Mr Marwan said yesterday that a strong belief in Islam would have stopped him from committing suicide. They said that his sister, Azza, had seen him less than two hours before he died, and that he was in good spirits.

Ramzi Dalloul, a Palestinian businessman who had known Mr Marwan for 15 years, said: “Ashraf was a good, kind and knowledgeable man, and was a religious person, dedicated to Islam. He would pray often and did not consume alcohol. He would always go on pilgrimages to Mecca. He could not have committed suicide. He would have known that it is expressly against Islam and he would not have done something like that.”

Charles Riachy, another close friend, agreed. “He was my friend, and was a wonderful father and husband. I do not think that he would have committed suicide. It would have been out of character,” he said.

Essam Abdel Samad, head of the Union of Egyptians in Europe, said Mr Marwan’s maid had told him that she was the only other person in the flat at the time of the death. “She said she was working in the kitchen and he was in his office and the first thing she knew was when someone came to the door and said he had fallen,” he told an Egyptian TV station.

Police are working on the possibility that Mr Marwan, 63, may have taken medicinal drugs that made him faint. He had had three heart operations and, according to Mr Riachy, “had been very unwell. He had aged a lot over the last five years because of illness. He may have become weak and fallen.”

Mr Marwan grew up in Cairo and was the son of a military officer in Nasser’s Presidential Guard. He married Mona, Nasser’s daughter, in 1966 in a lavish ceremony, and after the President’s death became a political and security adviser to President Sadat. He moved to London 25 years ago.

Historians claim that Mr Marwan was recruited by Mossad, the Israeli intelligence agency, and helped to alert Israel about an impending attack by Egypt and Syria in 1973. Others believe that he was a double agent feeding misinformation.

Before his death Mr Marwan was the subject of an inquiry into the sale of shares to Roman Abramovich, the owner of Chelsea Football Club.

Relatives gathered at his home yesterday and comforted his widow. His body will be flown to Egypt for burial once police and the coroner release his body.

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