SOME time after the operation, Sergeant Stephan Thorne responded to a survey and described himself in terms he found shocking: 'White, heterosexual and male.' 'Oh, my God,' he thought. 'I've joined the enemy.' Sergeant Thorne, a 10-year veteran of the San Francisco police force, had not joined the force as a man or as a heterosexual - he entered as Stephanie Thorne, a gay female officer. Thorne's story is all the more compelling because he then decided to go public about his sex change in one of the most male-dominated and macho professions in the United States. He is not a crusader, but he refuses to be silent about his experience because he believes too often transsexuals disappear after their operation, escaping past lives and carving new ones out of fear and shame. 'I think the closet is a terrible place to live,' he said. 'I think they become prisons - I won't live there.' Today, at 40, the changes Thorne has undergone are convincing: his body shape, including a spare tyre around his mid-section, broad shoulders and a somewhat clunky gait, all point to his being a man. Thorne said he had always wanted to be a man and felt betrayed by his body while growing up. 'Imagine yourself at puberty sprouting breasts and beginning to menstruate,' he said. Stephanie Thorne had never felt comfortable in women's clothes and had often been mistaken for a boy when she was a young girl. At 15, she 'came out' as a lesbian at her high school, in Lincoln, Nebraska - not known as one of the country's most liberal communities. When word reached the school's administration, Thorne was sent for psychological testing. When she was caught tacking up notices about local gay events at school, she was once again hauled into the principal's office, this time given an ultimatum: see a therapist of the school's choosing or be expelled. She refused. She believed their aim was to try to 'convert' her to heterosexuality. With two years to graduation, she signed up for night school and started a full-time job. Although she had decided to undergo a sex change operation when she was 17, she veered from that course during her early 20s. 'I began to think maybe I didn't have to become a man, maybe I just needed to take power as a woman and a lesbian,' said Thorne. In 1979 Stephanie moved to San Francisco - a place where she hoped she could fit in and feel happy. 'I thought if I finally came to the gay Mecca everything would be wonderful - wrong. 'In Nebraska everyone needed each other. It was not even a matter of being gay. If you were a feminist, if you were political or sort of slightly to the left, or working for minority rights you banded together. 'Here if you don't conform to the community's idea of what you should be, then forget you - get out. It's very intolerant,' said Thorne. Joining the force was considered an act of defiance. 'I was considered a traitor in the lesbian community,' Thorne said. 'I had joined the enemy.' Thorne became an officer in 1984, when the San Francisco police department was actively recruiting gays and other minorities. She distinguished herself on the force, was promoted and spoke out on women's issues as president of the Women Officers' Network. But despite outward successes, Thorne was becoming increasingly unhappy with her life. She acknowledged her feelings of masculinity by dressing more and more like a man and gained more than 25 kilograms. 'I think by gaining all that weight I was trying to hide. I continued to feel more isolated and less able to connect with people,' Thorne said. One night she broke down while discussing these feelings with her lover. She sobbed uncontrollably for hours, but emerged with an understanding of why she was unhappy. 'It was an epiphany. I realised I should have been born male, I was grieving for the fact that I was not a man.' Almost 20 years after initially realising she wanted a sex change, Thorne finally decided to go through with it. She was nervous, initially fearing she would either be fired, hounded or harassed from the force. In the end, Thorne decided she had to proceed. 'I decided to fight for it, because I had to do this. This was not optional.' Legally, she was protected by San Francisco anti-discrimination laws, but without the support of the force and her colleagues, she knew the transition would be doomed to failure. She first told the San Francisco Chief of Police of her plan and found, to her surprise, he was supportive. She then approached Michael Dower, the captain of her station, a man who had held his position for less than three weeks when Thorne dropped this bomb at his doorstep. But Dower 'could not have handled it better,' Thorne said. 'He was wonderful.' Days after the announcement, in May 1994, Sergeant Stephanie Thorne, who had already been taking hormone injections which had deepened her voice, and caused significant changes to her body, left for sex reassignment surgery. A month later Thorne returned as Stephan. He had undergone a double mastectomy and chest reconstruction in that time and still intends to undergo genital reconstruction which will allow him to have a sexually responsive penis. Thorne said the hormone treatments affected him far more profoundly than surgery. Not only did the treatments lower his voice to the point where people began calling him 'sir' on the telephone, but his body began to transform markedly. He began to grow hair on his legs, arms and chest and fat he carried on his body began to settle in different places, moving from his hips and thighs to mid-section and upper body. He knew the hormones would 'increase his libido', but he was not prepared for the urges he felt in the first months of his treatment. He recalled feeling shocked by his own desires. 'I had become a pubescent male,' he said. This from a self-described 'die-hard feminist', someone who had fought much of her life for women's causes. Another change was an assumed bond between males. 'I'll go to domestic disputes and the male will speak with me differently now and assume that there is common ground between us because we are both men.' Perhaps, but if so, it is a bond Thorne is only just discovering and one that is providing him with more insight into a sex he once considered 'the enemy'.