Thi Thi Nwe waited three days until the girl was left unguarded in her hospital bed to approach her, the first step in a months-long process highlighting the challenges of protecting child servants.
The NGO worker first saw the teenager, whose back and torso were covered with livid burns, in December but there was always someone by her bedside ensuring no one could get close.
"When I saw her, she covered her chest with a cloth. Her back was covered with a bandage," Thi Thi Nwe told AFP during a recent visit to the southern city of Mawlamyine.
"Some people... asked me not to talk to her because her guardian didn't like it. Then I suspected something. It's not right if they don't even want any questions asked."
When she and her colleague finally managed to approach Khin Khin Tun the 14-year-old was too scared to talk, saying she had spilt boiling water on herself by accident.
It was only when they turned leave that the girl blurted out her employer had attacked her, the latest incident in what she says were years of abuse inflicted on her and her sister.
Today her former boss, Aye Aye Soe, is on trial for grievous bodily harm after Thi Thi Nwe persuaded the girls' aunt to press charges.
The case is a rare prosecution under Myanmar's crumbling legal system, which provides little protection for tens of thousands of children thought to work as domestic servants.
Tackling the issue is one of the key challenges facing the new democratically elected government as it seeks to heal the country after 50 years of oppressive military rule.
Experts say many victims are too scared to complain, fearing they will not be believed or their abusers will lie to get them thrown in jail.
Authorities regularly turn a blind eye to allegations against wealthy and powerful families in return for bribes, while police are often under-resourced and ignorant of the law.
When AFP visited a recent training session, officers were given comic book-style leaflets with pictures of children being beaten and abused to help them understand.
Lawyers also face an uphill struggle as there are no specific laws covering domestic helpers, meaning cases must be brought under human-trafficking legislation or treated as common assault.
Mawlamyine Justice Centre director Thurayn Thee said the system was full of "weakness" and blamed the government for not doing enough to protect child workers.
Anyone who does stand up for victims can face harassment and threats.
Thi Thi Nwe said the accused's mother has tried to intimidate the girls, following them and berating them for being "ungrateful" to their former employers.
"We are not afraid," said her colleague Win Win Maw, who is also working on the case.
"We try to keep in mind that we are all equal in the eyes of the law."