Roy Bennett, the treasurer of premier Morgan Tsvangirai’s party, is accused of plotting to assassinate President Robert Mugabe in 2006 in a conspiracy already dismissed by the courts in an earlier case.
Attorney General Johannes Tomana’s case hinges on testimony from former policeman Peter Hischmann, who prosecutors say was found with an arms cache funded by Bennett as part of a scheme to kill the president.
Hischmann, who Bennett’s lawyers say was tortured into testifying, had failed to appear in court when summoned to testify at the trial’s last hearing in November.
After inspecting an array of weapons that prosecutors presented as evidence, Hischmann disowned many of them, including six submachine guns and some teargas canisters.
Two uzi submachine guns he said were his, but insisted they were properly registered.
Hischmman, who was a police officer in colonial Rhodesia, said he had never met Bennett, and accused police of seeking to fabricate a conspiracy.
Police were "alleging that there was correspondence between the accused and myself, alleging that the accused and I were communicating with intention of committing acts of sabotage," Hitschmann said, denying all the accusations.
Tomana said asked the court to impeach Hischmann as a witness, saying he had contradicted his earlier testimony to police.
"He is not to be accepted as a favourable witness," Tomana said. "The docket I have clearly shows a departure of statement he made to the police."
Bennett’s co-accused, Giles Mutseyekwa, who is now home affairs minister in Zimbabwe’s power-sharing government, was acquitted of the charges in the same year.
Bennett was Tsvangirai’s pick for deputy agriculture minister but Mugabe has refused to swear him in saying he had to be cleared by the courts first.