State prosecutors have applied for permission to retry the former head of the country's apartheid-era germ warfare programme, Dr Wouter Basson.
Dr Basson said he was a scientist obeying orders
Dubbed 'Dr Death' by the South African media, in April 2002 he was found not guilty of 46 charges of murder, conspiracy and drug trafficking.
State lawyers are asking South Africa's Constitutional Court for a retrial.
They argue that the white judge in the original trial was biased. A Supreme Court appeal was rejected in 2003.
During the two-and-a-half year trial, witnesses had testified to a catalogue of horrific killing methods including "smart" poisons, which would only affect black people.
It was also alleged that Dr Basson had hoarded enough cholera and anthrax to start epidemics.
Witnesses testified that he had developed sugar laced with salmonella, cigarettes with anthrax, chocolates with botulism and whisky with herbicide.
Dr Basson said he had been following orders and portrayed himself as a scientist who had sought ways to combat plant disease potato blight and an epidemic of hepatitis A.