Scotland Yard will open an investigation into the mysterious death of Dr. Ashraf Marwan, an Egyptian businessman identified as the Mossad agent who tipped Israel off on the eve of the Yom Kippur War about the coming surprise attack. Marwan, 63, was found dead outside his home in London's Mayfair neighborhood on Wednesday. "It is understood he may have fallen from a balcony, but enquiries into the circumstances surrounding the death do continue. A post mortem will be scheduled in due course - likely to be at Westminster mortuary. An inquest will open and adjourn in due course - likely to be at Westminster Coroner's Court," police said. The death is being treated as unexplained at present. Marwan's link to the Mossad was publicly revealed four years ago by Israeli researchers and confirmed this month in a Tel Aviv judicial proceeding in which Maj.-Gen. (res.) Eli Zeira, who was the head of IDF Military Intelligence in 1973, was found to have leaked Marwan's identity to journalists and others. Marwan's access to wealth and power stemmed from his marriage to the favorite daughter of Egyptian president Gamal Abdel Nasser. His father-in-law made him a roving ambassador and Marwan began dabbling on his own in arms deals. In 1969, he entered the Israeli Embassy in London and offered his services as an agent. Despite deep initial skepticism about his motives and fears that he was a double agent, the Mossad soon found him to be supplying priceless political and military information from the heart of the Egyptian establishment, some of which could be confirmed from other sources. Although he demanded and received large payments, Israeli officials believed his motivation lay more in the psychological realm than in greed. Two days before the Yom Kippur War started in October 1973, Marwan in Cairo telephoned his Mossad handler in London and let drop a code word for imminent war. He asked to meet with Mossad head Zvi Zamir the next day. Zamir flew to London and met Marwan in an apartment late that night, Yom Kippur eve. Marwan revealed that the Egyptian and Syrian armies would attack the next day. The warning, passed on by Zamir, reached Israel in the pre-dawn hours. After intensive discussions within the political and military hierarchy, prime minister Golda Meir authorized mobilization five hours before the attack got under way. This proved sufficient for the first reserve tank units to reach the Golan Heights just as Syrian divisions were breaking through the thin defenses there. In desperate battles, the IDF stopped the Syrian army and then pushed it back. Marwan subsequently became a high-flying businessman based in London, engaging in often mysterious international dealings. Despite the allegations in recent years about his Mossad connection, he continued to visit Egypt, where he was a prominent figure in society and business. Zeira claimed in a book published a decade ago that the Yom Kippur informant had actually been a double agent, also working for Egypt and feeding Israel disinformation. Zeira did not name the agent but gave hints in the book and in conversations with journalists that led easily to Marwan. Retired Mossad chief Zamir criticized Zeira for leaking the agent's identity and Zeira sued him for libel. The two men agreed to have retired Supreme Court justice Theodore Or act as arbitrator. During the proceedings, Marwan's identity was confirmed. The judge found that Zeira had indeed leaked the agent's identity to the press, violating one of the prime rules of espionage. Zeira was forced to retire after the war when the Agranat Commission placed the principle responsibility for Israel having been caught by surprise upon him, then-chief of General Staff Lt.-Gen. David Elazar and four others. Or speculated that Zeira may have been attempting to mitigate his guilt by sharing the blame with the Mossad for allegedly having used a double agent. Zeira claimed that the agent had waited until the last moment before issuing his war warning. Brief as it was, however, that warning almost certainly saved the Golan Heights for Israel.