In the past few days I've heard some very interesting news, including the best information I've yet received on M's disappearance.
I've been in touch with an English girl who was living in Vietnam when M was taken, and conducted some investigations of her own. This is what she learned:
There was an Australian student who had been living in M's town for three months in early 2011; he returned home, and sponsored M to attend school in Hanoi. M planned to go to Hanoi around the 15th July 2011 with her friend who was also enrolled in the school. However, M's father fell ill, and she decided to stay at home for a few more days to help her family.
M disappeared the next day, the 16th July 2011, and nobody has heard from her since.
From another source, it seems that M had recently been spending time with a local Hmong boy; nobody seems to know exactly who he is or which village he's from. It seems he offered her a ride to her village on the back of his motorbike, but took her to the Chinese border instead.
It seems that human traffickers will pay the local equivalent of up to one hundred US dollars for a kidnapped girl.
M telephoned a Hmong girlfriend of hers (from the back of the motorbike, it seems), who was her last known contact in Vietnam. When her friend tried to call her again, M's phone was switched off, or out of range.
M's sister had also been taken to China, and was able to return. Hers was a similar story: a Hmong boy she'd been spending time with offered to take her somewhere on the back of his motorbike. She was then drugged, and regained consciousness only in China. She and a friend were able to escape and contact the Chinese police, who helped them return home.
The girls who are able to return to Vietnam are, tragically, often stigmatised and outcast from society. This is partly due to the highly traditional nature of the Hmong communities, the perception of a girl who has been violated as unclean, and the fact that some girls return only for the purpose of recruiting others. (Some girls cross the border of their own volition, lured by the promise of employment).
This raises another difficult issue: although raising public awareness of M's plight may help us bring her home, she might not want a lot of attention if and when she comes back. M's sister has since returned to China; whether or not of her own volition is unclear.