Hunan Provincial authorities launched on Monday an investigation into the 18-month detention of a mother who tenaciously fought for justice for her daughter who was forced into prostitution six years ago when she was only 11 years old.

Tang Hui was handed the administrative order to remain at a reeducation-through-labor center on Thursday.

Tang was apparently relentless in seeking the death penalty for seven people who were charged with forcing her daughter into prostitution. The Hunan Higher People's Court in June sentenced two of the defendants to death, four were given life terms and one was sent to prison for 15 years.

Dissatisfied with the leniency of some of the sentences, Tang refused to leave the Yongzhou Intermediate People's Court building for 15 days, the Yongzhou Public Security Bureau said on Sunday. Her conduct severely disrupted public order and court proceedings, the bureau said in its statement.

Tang is held at the center under administrative detention. 

A team from the Hunan Politics and Law Committee was sent to investigate on Monday after learning of the controversial detention of Tang Hui.

"There is no reason to send Tang to the center." said Hu Yihua, Tang's attorney. "I'm taking every possible measure to free Tang."

The case caught public attention with many people suggesting that it appears the justice seeker has become a victim of the justice system.

"Tang is a desperate mother who suffered a lot from her daughter's tragedy," said Deng Fei, a well-known journalist and promoter of children's right.