Former South African prosecution boss Bulelani Ngcuka has denied conspiring against African National Congress (ANC) president Jacob Zuma.
"I have stated -- and wish to reiterate this point -- that I have never been party to any conspiracy to frustrate the political ambition of Zuma to ascend the highest office in the land," he said in a statement on Wednesday.
Acting national director of public prosecutions Mokotedi Mpshe announced on Monday that charges of fraud and corruption against Zuma were being dropped on the grounds of collusion between McCarthy and Ngcuka.
Among other things, manipulation and abuse of process had been found in transcripts of telephone calls between them, he said.
The conspiracy was apparently aimed at securing their preferred candidate as president.
Ngcuka has expressed dismay and disappointment at Mpshe's assertions.
"I hold the National Directorate of Public Prosecutions (NDPP) in the highest regard as one of the pillars of our democracy whose independence has to be jealously guarded and, accordingly, I would never do anything or be party to anything that seeks to undermine the integrity and independence of this institution," he said.
"In my capacity as head of the NDPP, I had the opportunity to prosecute Mr. Zuma. I did not."
Ngcuka said he had not been given access to any of the transcripts on which Mpshe's assertions were based, but was questioned about them by the NPA a week ago and responded "to the best of my ability".
"Importantly, I was told that these 'recordings' were part of oral representations that the defense team had made as part of their case for dropping of charges against Mr. Zuma.
"On that occasion, I was informed that I was being approached by the NPA as a possible witness in the matter of the application for the stay of prosecution by Mr. Zuma, should such a process ensue."
While Ngcuka initially indicated that he would respond to the allegations against him, he said he later declined on the advice of his legal advisers.
He did so because he was not given access to the transcripts and would, therefore, be unable to fully and accurately respond to the questions, he said. "Selective 'excerpts' had the potential to distort context."
It was also not clear to him whether the recordings were authentic and legally obtained, and how they had come to be in the possession of Zuma's lawyers.
"I requested the NPA to investigate the legality of the monitoring and interception of my private conversations," he said.
Ngcuka said there was further "huge potential" for an "ambush" in responding under oath to questions distilled from an account of third parties of recordings they had listened to in the offices of Zuma's lawyers.
"The selective use of extracts from various discussions we witnessed during the NPA media conference... confirmed my worst fears of a potential for an ambush," he said.
Ngcuka found it "disturbing and inexplicable" that the transcripts made available to the media at the briefing were not put to him in his two meetings with the NPA.
"Whether the NDPP and other members of the NPA had the recordings and transcripts at the time, I do not know. I however contend that natural justice and fairness demanded that at the very least the particular extracts the NPA relied upon should have been put to me for a response," he said.
He would reserve his comments on the transcripts pending the outcome of further investigations into the matter, which appeared to be underway.
However, he was concerned that, by the NPA's own admission, no official transcripts of the recordings were available; some of the discussions at issue had been paraphrased; and the NPA alone had decided which parts were relevant.
In addition, the NPA had added comments on the recordings to explain issues it considered not clear, stressing that these comments were "tentative" and subject to further investigations.
In announcing the withdrawal of charges against Zuma, Mpshe said the merits of the case had not been dealt with and the decision did not mean Zuma was acquitted.
Zuma, meanwhile, has said he finally feels vindicated after eight years of investigation.
"The investigation had brought untold pressure on the entire Zuma family and relatives. And I want to thank those who believed in my innocence," he said shortly after he appeared in the High Court in Durban for its endorsement of the NPA's decision on Tuesday.
Independent Democrats leader Patricia de Lille has laid charges of improper interference in the work of the NPA against Ngcuka and McCarthy.