(CNN) -- Finally going back home to Indonesia this month after toiling for 13 years in Hong Kong, migrant worker Riyanti was looking forward to being reunited with her child.
But as she waited at the airport departure gates she couldn't help noticing the distressed condition of one of her compatriots.
With blackened skin and obviously in pain, Erwiana Sulistyaningsih told Riyanti her condition was due to a skin allergy exacerbated by the winter cold.
But when she couldn't stand up to walk to the departure gate, Riyanti knew that something was seriously wrong.
Erwiana was so weak, Riyanti put her on a trolley to wheel her to the gate. Eventually, she had to help her onto the plane.
Allegations of torture
"She said, 'I'm scared.' I asked her why and told her she didn't need to be scared because I was there to help. I immediately took photos of her hands, her body. I asked again, are you sure these are really from allergies?" Riyanti told CNN.
"Then she told me: 'The truth is I was tortured by my employer. She beat me up and didn't give enough food to eat. I got very weak so she sent me home.'
"I told her we should report it to the police but she said 'No, I'm scared because she threatened to have my parents killed by her husband's friends.'"
Riyanti, one of four Indonesian workers who came to the aid of Erwiana at Hong Kong Airport, traveled with the ailing domestic helper to her home in Ngawi, East Java, and stayed on to help her.
"Because I'm already involved, I refuse to be silent," Riyanti said.
"I can't accept what happened, that kind of torture. How she suffered while she was walking, while she was sitting (at the airport). I wonder what she went through during the months she worked there."
Erwiana's case is now at the center of an investigation and protests by thousands of people who rallied in Hong Kong on Sunday to demand justice for the young Indonesian maid.
Allegedly beaten by her employer in a case that has sparked outrage and a police investigation into accusations of torture, Erwiana's plight has drawn attention to the risks faced by migrant workers in Asia and the Gulf regions.
The employer also threatened to kill Erwiana and her family if she revealed the abuse she suffered, Eni Lestari, head of the Indonesian Migrant Workers Network, told the South China Morning Post.
On Monday afternoon police arrested a 44-year-old housewife believed to be connected with the case at the Hong Kong airport. Police combined Erwiana's case with that of another Indonesian maid who was allegedly abused by the same person. After finding similarities in the cases, officers decided to pursue both investigations together, said Chan Wai Mun, the police chief of Kwun Tong, a district of Hong Kong, in a press conference Monday night.
Erwiana is now recovering from her injuries at a hospital in Sragen, a city in central Java, after flying out from Hong Kong in early January. The maid had suffered extensive injuries but her condition was stabilizing, the South China Morning Post reported.
'Live-in law' questioned
At the heart of the issue is a Hong Kong law that requires domestic helpers to live with their employers. While domestic helpers in Hong Kong are guaranteed a minimum wage of HK$3,920 ($505) a month under heavily policed labor laws, support groups say the live-in law contributes to abuse.
Hong Kong's Mission For Migrant Workers (MFMW) released a study last year based on interviews with more than 3,000 foreign domestic workers. It found that almost one third had no proper accommodation within the house.
"They do not have their own room provided and have to either share the bedroom with other members of the household or sleep in common areas of the apartment, such as the living room, study or playroom where there is very little privacy," the study reported.
"Some even sleep in unsuitable spaces such as the bathroom, toilets, veranda, corridor, kitchen and storage rooms, with only makeshift beds on top of ovens, cupboards or bathtubs. There are foreign domestic workers that are forced to share the room with young adult male members of the household," it added.
MFMW director Cynthia Ca Abdon-Tellez told Hong Kong media that the government requirement that maids must live with their employer meant they had nowhere to run when they were abused.
She said the decision should be left to the employers and the maids whether they live together.
She also urged the government to scrap a policy that requires domestic helpers to leave Hong Kong just two weeks after their contracts expire, saying it did not give workers enough time to find new work.
"It often forces the helpers to endure abuses so they can hold on to their jobs," she said, adding that they needed the jobs to support their families back home.
CNN's Anna Coren, Anjali Tsui, and Kathy Quiano contributed to this report