Mbuso Ndlovu allegedly killed his elder brother during a quarrel and buried him in the backyard of their Dlamini home.
A year later he allegedly wrung the neck of another family member and hanged him to make it look like suicide.
Ndlovu has pleaded guilty to the first murder charge in the Johannesburg high court but denied killing the second family member, the son of one of his older brothers.
The court heard that general disrespect, continued quarrels over rules and the running of the house led to the killings. There were four brothers in the family.
Mbuso is on trial for the murders of his older brother, Thokoza Ndlovu, in 2006 and his nephew Sandile Ndlovu in September last year.
Another of the brothers, Khanyani Derrick Ndlovu, told the court that Mbuso had confessed to him a few months after he had killed Sandile.
"We believed that Thokoza had gone missing," Khanyani said.
"I was surprised when he told me he had killed him by chopping him with an axe and had buried him in the yard. He also surprised me by revealing that he had killed Sandile by twisting his neck and then hanging him.
"I then called all relatives and the police to the house to hear for themselves. He was arrested."
Khanyani said he had his own house in Kagiso.
"My brother told me during his confession that the axe got stuck in Thokoza's head and he struggled to remove it.
"He said there was a lot of blood but he cleaned it up before burying him."
He said a dog had dug up bones in the yard in 2006 and they had identified the skeleton, which was later exhumed by the police, as that of his brother Thokoza.
He said police investigations failed to lead to an arrest until his brother confessed last year.
Khanyani said he left the Dlamini house because there were always fights and arguments.
He said the house was later sold and each of them, including Mbuso, got R50000 from the proceeds.
Earlier, the current owners of the house described how their dog had dug up human remains in their yard.
The trial continues today.