Bangkok (CNN) Yu Yanhua hasn't been back to her apartment in days. She's been too frightened, she says, after at least four dissidents of Chinese origin were arrested or simply disappeared from Thailand in the last four months... only to resurface back in China in the custody of the government. Yu is a pro-democracy activist who fled to Thailand last year to escape government repression in China. "I thought I would get protection in Bangkok, that I wouldn't have to live in fear of being arrested all the time," she says, bursting into tears. Now she lives in fear of being snatched off the streets by Chinese agents.