The school's owner, aged 59, and its principal, who is 27 years old, were arrested after Kamohelo Pitso, 17, was found dead.
His mother, Makhotso Pitso, said the family wanted to know why her son was killed.
She said her son disappeared from her Botshabelo, Free State, home last month. The boy's body was found on Monday in a veld. Police found 14 initiates aged between 16 and 25 at the initiation school.
"I waited for him to return and three hours later three young men arrived at my house and told me that Kamohelo has joined other initiates at their school," said the mother.
"A week later the school's owner came to my house demanding R1500 for Kamohelo's release and later demanded R3500 after he had graduated."
Pitso said she was shocked because Kamohelo's father had told the school's owner that he was opposed to the boy attending the initiation.
Police spokeswoman Constable Consolation Mokoale said Kamohelo's body was found near a hill outside Botshabelo.
"He had sustained serious injuries to his body," Mokoale said.
"There was blood in his mouth, his left elbow has a burn wound. We suspect that he could have died on Sunday and we were only informed on Monday by his principal."
In the suspects' possession, police found fake permits allowing the children to attend the initiation school.
l In another similar case, Daniel Thabatau, 29, his younger brother Lehlohonolo Thabatau, 26, Mohau Motumi, 24, and Sesing Chapi, 21, are expected to stand trial for the murder of Mthandazo Kuzwayo, 19, Morena Potsane, 17, Itumeleng Tshiane, 19 and Thembekile Motselebane, 18.
The deceased were assaulted on their upper bodies and their buttocks were burnt with hot iron rods, allegedly by Daniel and Lehohonolo Thabatau, Motumi and Chapi.
About 30 initiates were rescued from the illegal school. Eleven other initiates were hospitalised. - firstname.lastname@example.org