When Norzin Wangmo used her computer and mobile phone two years ago to communicate with friends about protests in Tibet, she had no idea it would result in her torture and a five-year prison sentence.
Detained soon after sending the messages, the 30-year-old Tibetan government worker and writer was accused by officials of using the technology to inform the outside world about civil unrest in Tibet.
After months in detention, during which her friends said she was tortured, the five-year prison term was handed down. Few other details about Norzin Wangmo, who leaves behind a young son, are known.
No one is sure how Chinese intelligence obtained the details of her communications. But the story is a frightening example of the dark side of internet espionage on the mainland, where people perceived to be a threat to the state are targeted, including ordinary Chinese citizens, scholars, human-rights workers, journalists, diplomats and businesspeople.
Many security experts who study China believe the government is being fed information by a loose and shadowy network that includes the hacker community, organised crime and other parts of government, including security agencies and the People's Liberation Army (PLA).
'The sheer amount of energy and resources the Chinese government has thrown at this is enormous,' says Lhadon Tethong, director of the Canada-based Tibet Action Institute, which helps Tibetans fight for rights, primarily through the safe exchange of information, using sophisticated technology.
Many victims of internet espionage are quick to point a finger at the central government.