A 76-year-old man has been arrested for allegedly killing his 73-year-old wife in Yuen Long - the second such case in two days. The suspect was arrested in a flat on Hong Kong Island yesterday afternoon, hours after his wife, Wong Nui-oi, was found dead in their 17th floor flat in Yuk Ping House, Long Ping Estate. The man was being detained at Yuen Long police station last night and no charge had been laid. The death of the woman came to notice when her son, 46, and daughter, 40, visited the flat at midday. A police spokeswoman said they entered the flat with a spare key but were unable to open the bedroom door, which was locked. Wong was found in bed when firefighters broke into the bedroom, police said. She was declared dead at the scene. 'No external wound was found on the body. Initial investigation showed the woman died from suffocation,' a police source said. A post-mortem examination will be held today. On Wednesday, Fung Yuen-cheong, 70, was arrested for allegedly murdering his former wife, Mui Sau-kuen, 48, in their flat in Lek Yuen Estate, Sha Tin. Fung appeared in Sha Tin Court on Thursday and entered no plea to the murder charge. He has been remanded in custody until July 6. The Social Welfare Department said care had been arranged for the couple's 15-year-old son as his relatives could not take care of him. Police commissioner Dick Lee Ming-kwai said on Thursday that there was a slight increase in reports of domestic violence this year compared with the same period last year.