The Viana family
From left, Geraldine Viana, Amaro, Gabriela Correia, Tony's daughter from a previous marriaga, and Tony Viana Facebook

A court in South Africa has heard how a 12-year old boy was forced to watch his mother being raped and both his parents killed, before being drowned in boiling water.

Two gunmen, 24-year-old Patrick Radebe and 21-year-old Sipho Mbele, have pleaded guilty to the murder of Amaro Jose Viana and his parents, Tony and Geraldine, at their home in the Johannesburg suburb of Walkerville on 1 October 2011.

In addition to the rape and triple murder, the two men confessed to attacking Tony Viana with a machete, killing the family pet, and robbing the premises before they left. An accomplice, Sphiwe Motaung, also pleaded guilty to robbery.

Radebe and Mbele were both employed by Geraldine Viana, and said their act was intended as revenge for her mistreatment of them.

Shocking

The attack took place after the three men broke in to the property and waited for Tony Viana, a 53-year-old engineer, to return home.

When Viana came home he was attacked by the gang, who assaulted him with golf clubs and a machete-like knife known as a panga, before tying him up and ordering him to open the family safe.

His wife and son later also arrived at the house, and were also tied up by the gunmen before being placed in separate rooms.

Geraldine Viana, 43, was raped before both she and her husband were shot dead.

Radebe and Mbele told the court they then turned to the victims' son after they realised he could identify them if left alive.

"We went to the bathroom and turned on the tap", the pair said in a statement.

"We gagged him because he was crying. We forced him into the bath face down, knowing that he would drown."

Before leaving the property, the robbers also sliced upon the dog's stomach as a parting gesture, the court heard.

Sentencing begins on September 6.