Tran Thanh Tu, stepfather of the girl, was detained for three months Friday, pending investigations into the girl's abuse. His wife, Lau Y Lau, is also being investigated on the same charge, but has been allowed to stay home to raise her small children.
The abuse came to light Wednesday after a neighbor discovered many injuries on the girl's body.
Tu and Lau got married in 2020. They took in the 7-year-old girl, Lau’s daughter, to live with them in February this year.
Tu and Lau admitted beating the girl because she often "messed with our personal belongings" and "threw food away."
Nguyen Thanh Phuong, a local official, said doctors were treating the girl's injuries and she had been placed under the care of the local women's union.