The night they arrived in their ground-floor room at the Simple+ Hotel in Taipei, the phone rang. A male voice speaking Mandarin asked for Wong, saying a "Hong Kong friend" wanted to pay him a visit. The boys said Wong wasn't available. Later, they asked at the front desk if the call had come from outside the hotel, said the 18-year-old Wong. The desk attendant said no, leading Wong and his friends to conclude that the caller had been inside the hotel and knew their room number.
"Even my parents didn't know which hotel I was in or the exact time I was arriving. But that guy knew the details," Wong told Reuters.
Over a period of two days, at least two men followed Wong and his friends. One came within about two meters to snap pictures of them on his mobile phone. When the boys confronted the man, he said he had been hired to follow and photograph them, but was not part of the media. Wong has pictures of one of the men, which he posted on his Facebook page. He said he didn't bother to report the incident to police.
Derek Lam, a student activist on the trip with Wong, said he suspected the men following them were trying to collect dirt to tar the pro-democracy movement. The man they confronted, he said, told them he had instructions to photograph them, especially if they did anything like visit "women."
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Chan Kin-man, a founder of the democracy movement, said several men took turns to monitor his movements in late September, just before the protests erupted. Chan, an associate professor of sociology at Chinese University, described the men as "middle-aged" and said they were positioned at a bus stop opposite his apartment complex. They stayed for several days, working in shifts around the clock.
'Trying to slip a tail'
Fellow academic Robert Chung, a Hong Kong University pollster, is accustomed to being attacked in the city's pro-Beijing press over his surveys. His work explores sensitive topics, including attitudes to political reform and feelings about national identity. But earlier this year Chung was stunned when a report in one of these newspapers revealed he was being followed.
A full-page spread in the pro-Beijing Ta Kung Pao newspaper in May accused him of reckless driving, including running an amber light and making illegal turns. The report included a number of photographs of his car on different streets on different days over a period of weeks in March. The report also carried a graphic showing the routes he took and quoted a private investigator saying his "driving methods are similar to those used by spies trying to slip a tail."
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For Chung, the level of detail in the article suggested expertise beyond the skills of muckraking reporters. "There was never any real evidence until I read that Ta Kung Pao story," Chung told Reuters. "I believe they are professional agents."
A spokesperson for the Ta Kung Pao chief editor said the report was done "independently" by the paper's reporters.
Catholic priests in Hong Kong say they have been approached by MSS agents seeking gossip on local clerics and church affairs, as well as information on the Vatican's thinking on China. The officers typically visit Hong Kong on tourist visas but make their identities clear, seeking discreet meetings in cafes and restaurants.
For To, apprehensive about the silver Mercedes following him, it was a simple test that convinced him he needed to go to the police. On Monday, August 11, he stepped out of his apartment building with his three-year-old son, turned right and walked down the street in North Point.
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Sure enough, one of the silver Mercedes was parked near his building. To and his son walked a few doors down into a small café. A man got out of the car and followed them, peering through the window.
"That's when I knew I had to act," said To. "This was not normal." That day, he went to the police.
To suspects one reason the police moved so fast after he reported the surveillance is that they might have feared for his safety. In February, on a street not far from To's home, one of his close friends, investigative journalist Kevin Lau, was stabbed in a triad-style attack. Lau was lucky to survive.
To had been quoted in one of the journalist's more controversial articles in a Chinese-language newspaper. To said police warned him he needed to be alert and offered him protection but he declined. Police in Hong Kong and the mainland have arrested nine men in connection with the attack on Lau.
In his written police report, To described first seeing the Mercedes about four cars behind him on the way to work at the Legislative Council on Wednesday morning, Aug. 6. It followed him whenever he changed lanes and slowed whenever he slowed, he told police. That day, he saw the Mercedes parked outside his workplace with two Chinese men sitting inside. The same car followed him home.
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The next day, Thursday, a second silver Mercedes followed him to the office and parked by a nearby building. Shortly before midday on Thursday, To left his office and drove to the Hong Kong Jockey Club at the Happy Valley race course, he said in his report. The Mercedes that had followed him in the morning tailed him to the prestigious club.
The next morning, Friday, the second silver Mercedes was back on his tail when he drove to work, he reported. This pattern continued until the arrests.
After the police swooped, To said, they told him they took the two men and the two seized cars to a nearby police station. The police told him the two men refused to answer questions. They also told To there was no evidence to charge the pair with any offence. "They assured me I would not be followed anymore," To told Reuters.
'All a misunderstanding'
As of the day of the arrests, one of the Mercedes that To reported to police was registered to a residential address in the container port district of Kwai Chung in Hong Kong's New Territories, according to Hong Kong Transport Department vehicle ownership records.
In an interview with Reuters outside his home in late October, the car's owner, Riky Li Kwok-ming, said the police had asked him to bring the Mercedes in for inspection. The police checked the vehicle and asked him if he had been following anybody, Li told Reuters. Li said the police allowed him to leave and he had not heard from them since.
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Li denied he was a current or former police officer. He said he worked for the Hong Kong government but declined to give details. Li also said he hadn't followed anybody or let others use his car. He said he had been driving on Tanner Road in North Point, where To lives, because his office was in the same area.
When asked if he had been conducting surveillance while his car was parked outside the government office complex, Li said: "Of course not, I was just picking up my wife." Li said his wife also worked for the Hong Kong government, but wouldn't elaborate.
Reuters later located Li's car in a marked parking bay in government offices in North Point. In a follow-up interview in the parking lot earlier this month, Li said he worked for the government logistics department and had been there for more than 10 years.
The Hong Kong authorities have yet to explain who was following To and why.
In his case, Riky Li Kwok-ming says the answer is simple: "This is all a misunderstanding."