Johor police chief Kamarul Zaman Mamat said the boy was admitted to the hospital on Dec 23 after fainting at a house in Senggarang, Batu Pahat.

He died at 6.40pm yesterday.

Kamarul said the boy, whose parents were in jail for a drug offence, had been looked after by his older sister, who left him under the care of a friend.

He said police had arrested two men and three women, including the 19-year-old sister and her husband. They have been remanded for seven days until Dec 31.

Kosmo quoted him as saying that he had just come from the morgue and it was “heartbreaking” to look at the condition of the body.

He told the daily the boy was found to have suffered injuries from a hot iron rod and had marks of being beaten, including on his genitals.

Police also seized several items, including a metal rod, a clothes hanger, a fan cover and a motorcycle stand, suspected of being used to abuse the boy.

The case was initially investigated under Section 31(1)(a) of the Child Act 2001, but was later reclassified for murder under Section 302 of the Penal Code, Kamarul said.