The man surrendered himself to the police last Thursday and was arrested for murder.
He appeared in court on Monday.
Du Plessis was murdered in his house in Flap Street in Voëltjiedorp in Brits on 27 May. His wife found his body when she arrived home from work.
His hands were tied with shoelaces and it appeared as if he was strangled. He also had other injuries.
Du Plessis’ cellphone, a safe containing a firearm, and his Nissan NP200 bakkie, loaded with watermelons, were missing.
The bakkie was later found abandoned in Letlhabile. Du Plessis was last seen alive with his two employees who disappeared after his murder.