A 75-year-old grandmother of eight has become an unlikely figurehead in the campaign against corruption in Vietnam.
Mrs Duc has received threats of violence to drop cases
At 1.45m (4ft 9in) tall and weighing just 40kg (88lb), Le Hien Duc has come to attention for challenging corrupt officials and alerting their bosses.
She recently complained to Vietnam's education minister that officials were taking money from school dinner services and cutting down on portions.
Corruption is seen as a major problem in the one-party communist state.
Some officials earning low salaries take bribes to supplement their income.
Last year, the Vietnamese transport minister offered to resign after his deputy was arrested amid a major official corruption scandal.
Dao Dinh Binh accepted responsibility for the embezzlement of millions of dollars of state money by his staff, who used it to bet on football matches.
The BBC's Steve Jackson says many people in Vietnam are afraid to complain directly to the authorities or believe their protests will be ignored.
But Mrs Duc has fearlessly taken on anyone in authority from lowly bureaucrats to government ministers.
If her complaints are ignored by officials, she tracks them down at home and confronts them.
She has had a traffic policeman demoted for taking bribes and recently persuaded the education ministry to investigate complaints that officials were pocketing school dinner money and cutting down children's portions.
When parents' complaints were ignored, Mrs Duc found out Education Minister Nguyen Thien Nhan's mobile phone number and called him.
Mrs Duc said she was now getting numerous requests for help.
"I've received letters and petitions from almost every province in Vietnam," she told BBC World Service radio.
"Some people travelled all the way from the south, thousands of kilometres to ask me to speak up about their rights to high-level officials."
Mrs Duc said she spent all her time and money on the cases that people brought to her.
She also has three telephones at her home to allow her to receive multiple calls and phone the relevant authorities.
"Judging from my age, my health and my small pension, I should have rested and taken care of my grandchildren," she said.
"But my mind is with the Vietnamese people and I think their rights should be protected."
Mrs Duc said she had received threats of violence to intimidate her to drop cases, but that she had no intention of quitting.