TOKYO (AP) _ She was an unusually successful career woman at a Tokyo power company by day, a prostitute by night. He was an illegal Nepalese immigrant.

Ever since their paths crossed in a seedy area of Tokyo, the murder case that resulted has fascinated Japan.

It has also raised criticism of the way that racially homogenous Japan treats foreigners, as well as its unusual attitudes about sex.

On April 14, 2000, a lower court acquitted Govinda Prasad Mainali, a 34-year-old Nepali, of murdering Yasuko Watanabe, 39, in a shabby Tokyo apartment three years earlier, citing lack of evidence. At the time of the crime, Mainali was overstaying his Japanese visa and illegally working at an Indian restaurant.

Acquittals in criminal cases are extremely rare in Japan, where officials usually only indict suspects they are nearly certain of convicting. Reports say that police also have been known to relentlessly pressure and sometimes beat suspects to win confessions.

Mainali was accused of strangling and robbing Watanabe of $324. He eventually admitted having sex with her and paying her money, but denied killing her.

Despite the innocent verdict, Mainali was held in prison as the prosecution appealed the case, something that wouldn't have happened to a Japanese defendant.

Japanese human rights activists called the case further evidence of the legal system's discrimination against foreigners, who are often viewed as second-class citizens in Japan's often closed society.

``Police detained him even after his acquittal. This in itself is injustice,'' said Shinichi Sano, who wrote a best-selling book about the murder case and its unusual victim, who worked during the day for Tokyo Electric Power Co. and at night as a prostitute in the Shibuya area of town.

``It's discrimination against foreigners, particularly those from developing countries,'' Sano said in an interview on Tuesday. He also said that police beat Mainali and his former Nepali roommates to extract confessions.

Big questions also emerged about the evidence.

Police believe that Watanabe, a trained economist with a degree from prestigious Keio University, was having sex with four men a night, including when she was killed.

Nevertheless, authorities are accused of ignoring pubic hairs of other men and condoms found in the apartment where the killing took place.

In December, the Tokyo High Court sided with the prosecutors, overturned the acquittal and sentenced Mainali to life in prison. The ruling generated widespread media coverage of the case, its two victims and the fairness of Japan's legal system.

Mainali has filed an appeal with Japan's five-justice Supreme Court. But it isn't expected to hold a hearing for two years.

Meanwhile, the case continues to draw media attention to pornography and the unusual life led by Watanabe.

Japan has long been famous for its reserve and its belief that appearance and propriety are important. But it also developed professional prostitutes reaching back to the tradition of geishas, who were trained to entertain and serve men.

Today, pornography has become ubiquitous at all levels of Japanese society. ``Love hotels'' that cater to illicit affairs are common, and women often are fondled by strangers on crowded subway and train lines.

Yet there is little sex education in Japan and few strong feminist groups.

Like Watanabe, some women also serve as hostesses in bars and clubs, earning money to flirt and serve drinks to salarymen who work long hours and rarely spend time with their own families. More and more lonely housewives are earning money by flocking to Japan's telephone sex industry.

But that wasn't supposed to be for women with successful careers like Watanabe.

Many people are puzzled about what motivated Watanabe to lead a double life. But Sano and others believe that her unusual success as a careerwoman in Japan was set back when another woman bypassed her in promotions. They say that prompted Watanabe to turn to a nightlife that began in a hostess bar and led to prostitution.