The only survivor of Tuesday's gassing tragedy in Tsuen Wan regained consciousness yesterday, apparently unaware his wife and children were dead. Chan Ying-cheung, 41, whom detectives hope can give details of the deaths, woke for about 10 minutes yesterday morning after 24 hours in intensive care. A detective said: 'He was conscious but could not speak clearly. He tried hard to speak but was too emotionally unstable. 'He jotted down a few characters on a piece of paper, asking if his wife and children were all right.' Nurses told him they did not know the condition of Ng Suk-yee, 29, On-yee, six, and Chin-bong, three. However, his wife and children, along with a 21-year-old son from Mr Chan's previous marriage and two tenants had died in a gas-filled flat in Tsuen Wan centre after apparently being given sleeping pills. The bodies were found in two sealed bedrooms with hoses attached to an LPG gas cylinder pushed through holes drilled in the door. Yan Chai Hospital doctors said Mr Chan's condition had improved from critical to poor, but he was still on life support apparatus. Police said Mr Chan was aware he was in hospital and could estimate the time, but doctors said he was not fit to be questioned. Mr Chan slipped into unconsciousness again in the late afternoon. His mother-in-law and relatives identified the bodies at Sha Tin mortuary yesterday morning. New Territories South regional crime unit detectives, who are in charge of the case, returned to the estate yesterday morning to interview neighbours. Electrical and Mechanical Services Department officers took readings from the gas meter in the Chans' flat to help determine when the gassing might have started. New Territories South crime division senior superintendent Ian Mackness said: 'There are many theories in the media. But we are not going to say anything more until we get the facts.' Initial police post-mortem examination results confirmed the victims died of suffocation but it might be early next week before further tests showed whether the victims had been drugged. Empty bottles of pills were found in Mr Chan's bedroom.