THE minute Peter decided to testify against the Sun Yee On triad in 1987, his life changed. Now, he says, he has become ''a prisoner of his own making and justice has turned against him''. The afternoon he agreed to become principal Crown witness in the case, he, his wife and young daughter were taken to a hotel in Kowloon and waved goodbye to a life they never wanted to leave behind. For the next three weeks, numerous statements were taken and evidence was sought from him to prepare for the month-long trial. When the hearing was over, the family were moved to a safe house of 300 square feet. The one-bedroom flat, shared with two police bodyguards 24 hours a day, was their home for the next 18 months. The safe house was previously a vacant office inside a police station, which had been converted into a one-bedroom unit. It is believed the station has two such units to accommodate witnesses. Once these facilities are exhausted, police will have to rentprivate flats elsewhere to house witnesses. ''The police safe house was far from being a dream home for anyone, but the only consolation was that it was really safe,'' said Peter. ''The main door was four inches thick and made of solid metal, all windows had bars on and the curtains were always drawn. We had two armed officers to guard us for each eight-hour shift. The only privacy we had was in our little bedroom. There were no cooking facilities and we had to live on takeaways for that 11/2 years.''