
Johor CID chief Kamarul Zaman Mamat said the third suspect was a brother of the stepfather.
The boy was found by his mother lying on the bathroom floor with one of his legs pinned under a large water container. He was then rushed to the Endau health clinic.
A post-mortem revealed the boy was tortured. There were cigarette burn marks on his body.
Kamarul Zaman said the case has been classified as murder.