A Hong Kong businessman who killed his wife and two sons before shooting himself in the head in Seattle had been taking a daily cocktail of anti-depressants, tranquil-lisers and sleeping pills, it was claimed last night. Fireworks dealer Sam Lau Lam-san, who ran his Causeway Bay business from America, had been in a 'downward spin' according to close friends in the US, but he had managed to hide it from family and employees in Hong Kong. The normally outgoing and cheerful Lau, 55, had become quiet, withdrawn and forgetful. He had lost nine kilograms and suffered insomnia. Lifelong friend Dennis Su, who went to the same Hong Kong school as Lau, said: 'His mind was gone. The medication finally snapped him.' The bodies of Lau, his wife Arlene, 49, and sons Sammy, 21, and Terence, 17, were found on Monday. Lau died from a single bullet wound to the head while the others had multiple stomach wounds. A handgun was found next to the bodies in a storage room of their home, in the affluent Bellevue suburb of Seattle.