THE week-long surveillance of ailing People's University professor Ding Zilin continued yesterday following her brief detention on Thursday. The 58-year-old academic's husband, Jiang Peikun, said his wife was suffering from heart problems and was too weak to speak. He said plain-clothes state security officers had been stationed outside their home since Monday and continued to harass them whenever they went out. 'When we left for lunch this afternoon they asked us where we were going. We asked for their identities, but they said that was not necessary,' he said. Mr Jiang said seven plain-clothes officers surrounded the restaurant where the couple had lunch. 'I don't know why they are doing this or how long it will carry on. Our friends dare not come visit us for fear of being questioned, searched or arrested,' Mr Jiang said. Ding Zilin, whose 17-year-old son was killed in the 1989 Tiananmen Square crackdown, compiled information on 96 victims killed in the massacre. Their names, in two separate batches, were published in the Hong Kong-based magazine The Nineties' June and September issues. The Hong Kong spokesman for Human Rights Watch/Asia, Robin Munro, said yesterday the relentless harassment and persecution of the couple by the Chinese Government was to prevent them from pursuing documenting the June 4 crackdown. 'Her only crime is to have a son who was killed on June 4, 1989, and to have the courage to compile the identities of victims,' he said. Mr Jiang said this was the 11th time since March this year that their house had been kept under surveillance. On Thursday, Ms Ding was taken by plain-clothes state security officers to a nearby police station after she refused to tell them where she was heading when she left the house. 'I think they are just angry that despite continuous tight surveillance, informations still got out and a second list of victims was published. They might also be enraged that Fang Zheng visited us just after he was denied participation in the disabled games and before he was sent back to Hainan Island,' Mr Jiang said. Mr Fang, a student of the Beijing Institute of Physical Education in 1989, had his legs crushed by an army tank in the June 4 crackdown. He was thrown out of the Far East and South Pacific Games for the Disabled held in Beijing this month.