Correctional Services spokesman Manelisi Wolela has denied allegations that student leader Mcebo Dla.
His friends were arrested and sentenced in 2004 after being found guilty of armed robbery and murder - but he disappeared without a trace.
The two, Mack Ledwaba, 26, and Steve Chauke, 25, were given to life sentences.
But their co-accused, Edson Zenzo Nduli, disappeared four years ago and only resurfaced last week.
Nduli, a 30-year-old Zimbabwean, was arrested last week when he tried to cross Beit Bridge back to South Africa.
He will now have to answer for the crime he allegedly committed four years ago.
The police said Nduli was implicated with Ledwaba and Chauke in the robbery and murder of a pensioner in Seabe village.
The village is near Marapyane in the KwaMhlanga area of Mpumalanga.
"The old man tried to defend himself with an axe but was shot dead," said police spokesman Hasting Chaane.