A FORMER KGB agent has been questioned by Macau authorities probing links between the enclave and the killing in Vladivostok of Hong Kong lawyer Gary Alderdice and his prostitute lover. Vladimir Rippin, who is suspected by intelligence agencies of having been involved in the trade of materials for nuclear arms, is understood to have known prostitute Natalia Samofalova and her associates in Vladivostok and Macau. Authorities said Mr Rippin, who holds a passport from the west African country Guinea Bissau, reappeared in Macau within days of the murders in the Vladivostok flat of Samofalova, 21. He was interviewed in Macau as part of an informal probe by Macau investigators into the trade in Russian prostitutes. Authorities in Macau have also identified a Russian man who arrived in Macau on the same day as Samofalova in August last year. They have been puzzled by his purchase of a new four-wheel-drive Vitara vehicle in Hong Kong, which was shipped soon afterwards to an address in Russia. ''There are the same Russian groups represented in Hong Kong as in Macau,'' an official in the enclave said. ''They come freely to Macau, but until recently they could not get visas for Hong Kong. ''Now they can freely visit Hong Kong. Hong Kong will see more of these people now, maybe not with Russian passports, but with Sierra Leone or Honduran passports,'' the official said. When Samofalova arrived in Macau last August she was the holder of a Russian passport issued weeks earlier on July 6. Her passport number, CM-I 386100, is considered significant as it corresponds sequentially to the numbers on Russian passports issued to other Vladivostok prostitutes in Macau, including one woman she arrived with, Olga Bogdacheuskaia. Samofalova's passport shows that she had not travelled outside Russia before, or at least not on her own travel document, which lists her status as single and names her parents as Vladimir and Naoiejda. Her application to be a dancer at the Skylight club in Macau was handled by an employment agency, called the Society of Support to the Enterprises of Macau. She was issued a Macau identity card, number 45698, and a six-month work visa. In March, the Skylight asked that she be given a six-month extension, which was duly granted. But in May, by which time Alderdice had fallen head over heels for Samofalova and was living with her at the Westin Resort on Macau's Coloane Island, Skylight withdrew its support and successfully appealed to Macau Immigration for the cancellation of her identity card and visa. Authorities in Macau have told the South China Morning Post that discreet inquiries were being made in the enclave so that ''we may learn some lessons'' from the murders in Vladivostok. In the Russian city, police have released without charge the main suspect in the murders. They have not formally asked Macau police for any assistance.