The South African government has asked the Constitutional Court to re-try an apartheid-era germ warfare specialist, nicknamed Dr Death, who has been accused of murdering political opponents under white rule.
Wouter Basson, who earned the epithet for his expertise in developing poisons, avoided prison in 2002 when the High Court in Pretoria acquitted him of 46 charges, including murder, drug trafficking and theft. He had been accused of trying to create "smart" poisons that would affect only blacks, and manufacturing enough cholera and anthrax to start epidemics.
He is also said to have ordered black political prisoners to be tied to trees and smeared with a poisonous gel to see if they would die. If they survived, they were killed by muscle relaxant injections.
He also developed sugar laced with salmonella and anthrax cigarettes. South Africa's chemical and biological warfare programme was the first to have been so publicly exposed and is thought to have been the most lethal of its kind at the time.
The government has spent more than £2m trying to prove Dr Basson's guilt, and it has now taken the case to the Constitutional Court. It argues that Judge Willie Hartzenberg, who presided over the 2002 trial, was biased against the state, and refused to listen to witnesses.
South Africa's Supreme Court rejected an earlier appeal in 2003 but the Constitutional Court later ruled that the government is allowed to argue that the judge was not impartial and that it is entitled to another, fairer trial.