He Peirong has been at the forefront of a bold and innovative campaign by Chinese activists to free Chen and his family from their lengthy captivity.
Dozens have braved beatings and detention to attempt to visit his home in Shandong province, though none got anywhere near it thanks to the heavy security presence.
He, from Nanjing, told Associated Press she drove Chen from Dongshigu village to a "relatively safe place".
Bob Fu of China Aid told the Wall Street Journal that he had been speaking to He on Friday morning when she told him public security was at the door and hung up.
Friends have been unable to contact her since then and her phone was switched off on Friday evening. Police in Nanjing said they knew nothing of the case.
One user on Sina's microblog service compared He to Spider-Man "bravely going to dangerous places. She has been beaten and insulted in [Dongshigu]. She keeps her faith and courage."
Fu said that another activist, who had collected Chen from He, had called on Friday to say he was about to be arrested but Chen was already safe.
Li Fangping, a rights lawyer who tried to represent Chen in his court case, told AP that state security had questioned him on Friday.
"It has been extraordinary – this is high stakes stuff," said Sophie Richardson of Human Rights Watch.
"None of these people will have gone into it without a pretty clear idea of what might happen to them as a result. That shows extraordinary courage on the part of activists who are extremely vulnerable to exactly these kinds of reprisals … In my view, the least other governments can do is stand with them."
Those who have attempted to visit Chen have described their cars being run off the road and thugs beating and punching. One described how she was hooded and kicked. Another was held and questioned on suspicion of drug trafficking. Some were robbed of their phones, money, documents and other valuables before they were dumped on remote farmland miles away.
Foreign journalists, who are generally much less vulnerable to such incidents, have also been roughed up, threatened with bricks and pelted with stones. Even a group of European diplomats who sought to visit was forced to turn back because they felt so threatened.
The film star Christian Bale was also shoved by guards when he tried to enter the village with CNN.
Faced with the physical violence, activists have tried other tactics such as hanging a protest banner on Shandong's representative office in Beijing, accusing it of hurting China's image. More recently a flashmob of couples – all wearing sunglasses like Chen's – gathered in the centre of nearby Linyi city.
Campaigners have also handed out bumper stickers with a stylised picture of Chen resembling Kentucky Fried Chicken's Colonel Sanders and the tagline "Free CGC". Graffiti artists have sprayed the images in various Chinese cities.
But people have also faced retribution even far from Chen's home. In Beijing, lawyers were beaten and detained last February after meeting for lunch to discuss how to help Chen. Others had been barred from leaving their homes to attend the event.