A 10-year-old girl whose decomposing corpse was found in a canal in Bangkok on Saturday was suffocated before her body was dumped underwater, the Institute of Forensic Science (IFS) confirmed Thursday.
It cannot be confirmed whether Pornthip "Nong Rung" Kulanant was sexually assaulted because of the state of the corpse due to long water exposure, said IFS chief Pol Maj Gen Pornchai Suthirakhun.
A forensic result contradicted her parent's story, in which they claimed they found the girl dead.
Provincial Police Region 1 commissioner Charnthep Sesawech said Pornthip had previously lived with her biological father and his parents in Phitsanulok until her father died.
Supaporn Nontra, 31, the girl's mother, later took the girl to stay with her and her new husband, Wajaran Thadsawan, 35, Pol Lt Gen Charnthep said.
Mr Wajaran and Ms Supaporn had admitted to assaulting the girl frequently claiming she was not obeying them and often told lies, he said. They added that in one month there were about 10 occasions in which the mother and the stepfather had beaten the girl with a rod and sometimes kicked her.
The girl was last beaten on the Wednesday before her body was found, in an incident that left her with a swollen mouth and an injured head, said Pol Lt Gen Charnthep, citing statements given by the parents.
According to those statements, the stepfather said he returned home in Samut Prakan last Friday evening to see the girl dead and he didn't know what to do with her, Pol Lt Gen Charnthep said.
Mr Wajaran and Ms Supaporn decided to wrap the girl's body in a quilt and together carried it to be disposed of in the canal, Pol Lt Gen Charnthep said.
Bang Sao Thong police said they expect to indict Ms Supaporn and Mr Wajaran for murdering the girl and concealing and disposing of her body.
Pornthip's grandparents, Pramul and Wallop Kulanant, arrived in Bangkok Thursday from their home in Phitsanulok's Noen Maprang district to take the girl's body home for the funeral.
Ms Pramul, the grandmother, said: "Her mother promised to take good care of her daughter. "That's why I let her go live with her mother.
"I never expected that my granddaughter would end up dead like this."
Pornthip was raised by her birth father and grandparents since she was three, when her mother broke up with her father, said Ms Pramul, adding that two years later Porthip's father passed away.
The girl's mother had requested to take Pornthip to live with her in Roi Et province about a year ago. Her grandparents agreed to let the girl live with her biological mother, Ms Pramul said.
Two video clips circulated on social media that are believed to have been recorded by the girl not long before she was taken to Samut Prakan.
"I miss you dad. Never thought you would have died and left me. I love you. I still do," Pornthip said in one of the videos.
The girl complained in another video clip that she felt sorry that her mother didn't come to pick her up to stay with her after her father died.
Pornthip's relatives on Thursday eventually agreed to take her body for a funeral held at a temple in Samut Prakan.