An American-based Hong Kong businessman killed himself, wife and two sons in their Seattle home, police said last night. The bodies of fireworks dealer Sam Lau Lam-san, in his 50s, and his family were found in a storage room on Monday. Police found a letter apparently written by Lau accepting full responsibility for the deaths. It mentioned personal and business problems, and spelled out what he intended to do. Detectives recovered a 9 mm handgun, believed to be the murder weapon. The family's relatives and Lau's workforce at Kwongyuen Hangkee Ltd in Causeway Bay were stunned by the deaths. Although Lau's business is in Hong Kong, he preferred to live close to his clients in the US. The bodies were discovered by a property agent visiting the home in the affluent suburb of Bellevue. It is believed the house was up for sale. Police said they had not found a weapon or any sign of a break-in. Lau's sons were in college and high school. His brother, Peter, said: 'His company had not heard from him for two days. They thought it strange because he normally calls two to three times a day. 'He was here only two weeks ago. At this moment we are trying to accept the facts, we are too startled. He would be the last person to make enemies in the whole world. He was a jolly good fellow. Everybody liked him.' Colleagues within the territory's fireworks trade paid tribute to Lau. Hop Kee Pyrotechnics director Wilson Mao Wai-shing said: 'He was a very charming man, diplomatic and very well-mannered. I always respected him. This is so sad.' It is understood Lau had been fighting a lawsuit in America following a fireworks accident which resulted in a death. His business largely involved importing and exporting Chinese-manufactured fireworks. A family of four were murdered in the same suburb in January. Two 17-year-old youths have been charged over that incident.