He was arrested on suspicion of stealing a car battery, a crime she says he was innocent of. Then as he emerged from a police van at court two weeks later, he collapsed and was dead within hours.
Yu Lwin Aung said the human rights commission has referred this case to the home affairs ministry but has yet to receive a response.
It's a similar story for Tin Tin Aye, who said she watched as a group of police beat her son, Khaing Min Wai, when they arrested him in June.
They took him to a police station, and the next morning she saw his dead body at the hospital, with marks and cuts on his face, she told VOA.
Mon Mon Cho, a lawyer who is advising Tin Tin Aye, said accountability is key to preventing more cases like this in the future.
"The government must take action against these violent people," she said.
Even though a civilian government came to power for the first time in decades following a huge electoral victory in 2015, the country's military-drafted constitution still puts the generals in charge of three key ministries, including home affairs.