Bangkok police charged a 20-year-old woman with severely assaulting her own son, four, after he reportedly soiled his bed last week. The child was in a coma at hospital.
Pol Col Teerasak Pinyo, chief of the Khok Khram station, said on Wednesday that the woman and her new husband were detained after the incident.
The assault charge was initially laid on the woman as police had yet to find evidence that her new husband also attacked the boy, he said.
The station chief said the boy was severely injured and in a coma. Police were awaiting a report from the boy's doctor before considering additional charges.
It was reported that the boy's biological father, 23, told police on Tuesday night that his son was severely assaulted and admitted to Bhumibol Adulyadej Hospital in Sai Mai district.
He was quoted as saying that he had separated from the woman two years ago and she had custody of the child.
According to the report, the father gave the following account of events. She phoned him on Sunday and asked for 100,000 baht for an urgent operation for the boy, who she said had fallen and knocked his head on a bathroom floor.
She concealed information about the boy's condition and the hospital. Later he found out by himself where the boy was being treated.
At the hospital he found his biological son had suffered two broken ribs and a broken collar bone, with more than 20 wounds -- both old and new -- all over his face and body.
The woman told him that her father had assaulted the boy, but the maternal grandmother told him later that the woman and her new husband had taken the child from the grandparents in May, media reported.
Police learned on Tuesday night that the boy was assaulted on Aug 12 -- Mother's Day in Thailand -- after he defecated in his bed. The stepfather beat him and his mother hit him with the spine of a book, causing multiple wounds all over his body.
Police said the mother confessed to the assault. Questioning of the stepfather was continuing.