Nigel and Johannes Plaaitjies are accused of killing the 77-year-old in her home in May last year.
The teenager has pleaded not guilty, while his uncle has yet to plead.
Rust’s husband found her body on their kitchen floor.
She had wounds to her face and had been strangled.
The Rust couple had financially supported Nigel Plaaitjies, who was a promising school athlete.
The teenager claims that his uncle, Johannes, forced him into a robbery at the Rust home because the uncle owed money to a drug lord.
