A TWO-TIMING policeman who suffocated his fiancee three days before their wedding and then tried to kill a potential witness received two life sentences yesterday. Chong Yan-yuk, 30, murdered Maggie Leung Mei-kee, 25, after telling her he wanted to call off the marriage registration ceremony because he was seeing another woman. He then attacked a friend of the family, who was sleeping in a nearby room, the High Court heard. Chong and Leung, an accounts clerk, had held a wedding reception banquet seven months earlier and were due to register their marriage officially on June 22 last year. But unknown to Leung, Chong, a policeman for nine years, had been having an affair with a 19-year-old student nurse, Siu Wing-yan. Chong eventually decided to confess to Leung about the affair after spending the night with her at her parents' flat in Wong Tai Sin ''I felt very agitated and felt unable to control myself.'' He said Leung had died after he pinned her down, pressing her head against a cabinet with his head for about five minutes. But a postmortem examination showed it was more likely he had struck her or held her down with his hands. When Chong realised he had killed Leung, he panicked and decided to make it look as though she had been killed in a robbery. As he ransacked the flat, he smashed open the door of a bedroom, unaware that a family friend was sleeping there. In the first of four attacks, Chong struck the woman, a 32-year-old nurse, repeatedly with a hammer after trying to smother her with a pillow. The woman said she had been so frightened Chong would kill her she had written ''Ah Yuk killed me'' and her signature on the wall after he had left the room. The former officer, who was based at Tsim Sha Tsui, admitted attacking the woman, but denied trying to murder her. But a jury found Chong guilty of murdering Leung and attempting to murder the second woman on June 19 last year. Chong, who was cleared of a third charge of indecently assaulting the second woman, showed no emotion as the jury returned its verdicts.