By the BBC's Carolyn Dempster Johannesburg

The man South Africa's media dubbed "Dr Death" was relaxed and smiling as he addressed reporters for the first time on Friday.

After an unremitting 30 months in the dock, Dr Wouter Basson was a free man.

A lot of what was said there [TRC] was conjecture, rumour-mongering and people who had motives of their own.

Dr Wouter Basson

In a wry comment on the wrongness of his trial, he said the R40 million ($4 million) the state had spent prosecuting him could have been better spent paying for and providing the anti-Aids drug Nevirapine to HIV positive pregnant mothers.

It was a painful twist of the knife for the state which has not yet conceded defeat in the legal battle and aims to appeal against the verdict.

A spokesman for the ruling African National Congress has described the verdict as an "outrage".

Prejudice

Dr Basson was head of "Operation Coast", the apartheid government's secret biological and chemical warfare programme.

Many of the original charges against him emerged from testimony to the Truth and Reconciliation Commission in its last months in 1996.

Witnesses testified to a catalogue of killing methods ranging from the grotesque to the horrific:

• "Operation Coast" sought to create "smart" poisons, which would only affect blacks, and hoarded enough cholera and anthrax to start epidemics.
• Naked black men were tied to trees, smeared with a poisonous gel and left overnight to see if they would die. When the experiment failed, they were put to death with injections of muscle relaxants.
• Weapon ideas included sugar laced with salmonella, cigarettes with anthrax, chocolates with botulism and whisky with herbicide.

The unit's plans allegedly included lacing cigarettes with anthrax

For a start secrecy still shrouds "Operation Coast".

Classified information on South Africa's biological warfare programme, which it developed with the assistance of British and United States intelligence services, was stored on CD-Rom.

The data was handed over to the incoming government of President Nelson Mandela by outgoing President FW de Klerk in 1994, and remains under lock and key.

Investigators in the case against Dr Basson never had access to the results of the apartheid chemical warfare research programme.

Dr Basson was re-employed by the South African National Defence Force in 1995 on the basis that unless he was kept "onboard", there could be no assurances "how he would use the knowledge he had acquired", the then Deputy Defence Minister Ronnie Kasrils said.

As a serving member of the force, his defence costs of about R10 million was paid for by the state.

Reluctant

In his judgement, Judge Willie Hartzenberg claimed the prosecution had failed to prove, beyond reasonable doubt, that Dr Basson was guilty of the 46 charges against him, including 19 of murder and conspiracy, as well as fraud totalling $5 million.

The picture that did emerge during the trial was that most of the murders in which he was implicated, were committed by agents of the apartheid state's Covert Co-operation Bureau, CCB, a secret unit of apartheid assassins.

What the CCB operatives claimed in court was that although they did the dirty deeds, it was Dr Basson and his team at the Roodeplaat Laboratories who supplied the poisons and the means to deal out death.

Yet Judge Willie Hartzenberg was reluctant to believe the evidence of these men.

At one point he claimed that Dr Basson had been the victim of an unrelenting witchunt, while a "repugnant" person like former military intelligence colonel Johan Theron, who testified that he had played a part in the murder of 200 members of the South West African People's Organisation, Swapo, remained a free man.

It was this attitude, and interventions from the judge that he was "bored to death" with all the documentation, and his refusal to travel to England to hear testimony from a former British secret agent, which prompted senior state prosecutor Anton Ackermann to accuse him of bias.

Appeal

Only 36 days into the trial Mr Ackermann demanded the judge recuse himself from the case.

Judge Hartzenberg refused.

The animosity between the prosecution and the bench increased to the point where Mr Ackermann refused to continue with cross-questioning and left his junior colleague to prosecute the trial.

But the legal battle is not over.

The two sides will lock horns again on 29 April, when the prosecution applies for leave to appeal against the verdict.