Green’s Dictionary of Slang

(S.Afr. prison) a prisoner.

1974		H. Levin Bandiet 8: An Afrikaans word [...] no longer in official use because considered derogatory. Unofficially – i.e. in common use throughout South African jails – a prisoner is called a bandiet. Plural bandiete.
1995		Mail & Guardian (Johannesburg) 29 sept. 🌐 One-time bandiet Carl Niehaus, now parliamentary boss of his former jailers [is] admirably rel;axed as the 40-odd bandiete arrive.
1998		Mail & Guardian (Johannesburg) 24 Apr. 🌐 One day another bandiet grabbed R40 I got from my relatives.