South African parents are murdered in their own home and son, 12, is drowned in BOILING WATER

Three men broke into the house in Walkerville, Johannesburg, assaulting and shooting dead Tony Viana (right) and brutally raping and killing his wife, Geraldine (left). They then tied up and gagged the sobbing boy, Amaro, second left, and pushed him into a bath of scalding hot water to drown him, 'because he would be able to identify them'. (Also pictured, Gabriela Correia, Mr Viana's daughter from his first marriage.)

A 12-year-old boy was drowned in a bath of boiling water by robbers who raped his mother before killing both his parents in a violent house robbery.

Three men broke into the family's home in Walkerville, Johannesburg, where they assaulted and shot dead Tony Viana, 53, and brutally raped and killed his wife, Geraldine.

They then tied up and gagged the sobbing boy, Amaro, and pushed him into a bath of boiling hot water to drown him, 'because he would be able to identify them'.

The family’s gardener, Patrick Petrus Radebe, 24, their domestic servant’s son, Sipho Mbele, 21, pleaded guilty to three charges of murder and one charge of rape each, reported Sowetan Live.

David Motaung, 20, pleaded guilty on Tuesday to robbery charges.

They then left the South African court and walked back their cells laughing, according to Beeld newspaper.

The family dog was killed by having his stomach cut open.

The men’s lawyer told Vereeniging Regional Court that they had broken into the house to steal and to get revenge for the way they had been treated by 42-year-old Mrs Viana, their employer.

The court heard that Mr Viana arrived home at the house to be attacked with a golf club and a machete-like 'panga' and ordered to open the family's safe.

He was tied up and his wife and son, who arrived shortly after, were tied up in separate rooms.

Mbele then raped Mrs Viana while Radebe helped restrain her by standing on her face before raping her too. They then shot her with her husband’s gun before shooting him in the head too, reported praag.org.

The accused admitted they then realised Amaro would recognise him.

Twisted: From left, Sipho Mbele, David Motaung and Patrick Petrus Radebe smiled in court as they admitted to their sick crimes

Torn apart: Amaro with his mother Geraldine and father Tony, who were shot to death by the robbers, along with Gabriela Correia, Mr Viana's daughter by his first marriage

Sick attack: Amaro, pictured with half-sister Gabriela, was tied up and gagged before being scalded to death

Their statement said: 'We went to the bathroom and turned on the tap. We went to [Amaro] him and gagged him because he was crying. We forced him into the bath face down, knowing that he would drown.'

According to Beeld, Mbele and Radebe admitted guilt on charges of burglary with the intent to steal, robbery with aggravating circumstances, the possession of an unlicensed firearm, the illegal possession of ammunition and intentional damage to goods.

From forensic evidence tendered in court, it was clear that the boy was held down in boiling water. The exact cause of his death has however not yet been determined by state pathologists. The boy’s hands and feet were tied.

The men will be sentenced on September 6.

Poignant pictures published on Facebook show the family, who are of Portuguese descent, relaxing together on holiday in the luxury South African resort of Sun City.

Appalling crime: The three men laughed as they walked back to their cells after pleading guilty at Vereeniging Regional Court, pictured