Mbuso Ndlovu continued living in the family home after he had killed and secretly buried his brother in a shallow grave in the yard.
Mbuso told the Johannesburg high court on Tuesday that he lived in the house for about six months after killing his brother Thokoza Ndlovu.
"I did not tell anyone I had killed my brother because I was afraid," he testified.
He confessed to killing his brother with an axe and that Thokoza had died on the scene.
"When his bones were dug up I decided to confess to Khanyisa's killing," he said.
Mbuso is also charged with the murder of his nephew Sandile Ndlovu, whom he allegedly killed a year after Thokoza.
But he has pleaded not guilty to Sandile's murder.
Dobsonville investigating officer Walter Sipho Magazi said the police had evidence that Sandile had been murdered.
"I can say he was murdered because there was nothing next to his body that he could have used to climb on to hang himself."
Magazi had earlier testified: "The killer tried to hide evidence by killing Sandile somewhere else and carrying his body to the bush near Braamfischerville, where he hanged him from a tree."
The trial continues.