The Scorpions investigation unit expects to wrap up the arms deal investigation by the end of next month, reflecting a strong desire to reach finality in a case that has taken years and dogged the reputations of several senior politicians, including Deputy President Jacob Zuma.

The case will most probably be finalised following the crossquestioning of Durban businessman Schabir Shaik, who last week lost his application to prevent enforced cross-questioning by the National Prosecuting Authority.

The Scorpions also intend cross-questioning Shaik at a different time on a separate case involving road contracts and former Transport Minister Mac Maharaj.

But while on the brink of closing the investigation on one front, another has opened up. The Scorpions intend investigating thoroughly a smear campaign launched against Scorpions boss Bulelani Ngcuka.

The smear involves the widespread distribution of an anonymous e-mail purportedly written by a disgruntled employee of the national directorate of public prosecutions, which is headed by Ngcuka and under which the Scorpions fall.

The e-mail, sent from a variety of internet e-mail addresses mostly hosted by Yahoo, levels a range of highly libellous allegations against Ngcuka and several other high-profile businessmen.

Ngcuka said yesterday the Scorpions already had a number of suspects in the case, and would investigate it aggressively. This would include approaching the authorities in the US, where Yahoo is based, in an attempt to track down the sender.

Ngcuka said there was no truth in any of the many different allegations made against him personally. In the past, he had tended to ignore personal threats, including death threats, in order to maintain a focus on the job at hand. But this e-mail was not only an attack on Ngcuka himself, but on the organisation as a whole.

Speculation in the press has suggested that the e-mail is linked to the arms deal.

But investigators have not ruled out the possibility that it could also be linked to other sources, including some prominent businessmen.

Ngcuka said that the cases now coming to a head would be "a test of character for the organisation". Once the investigations were complete, the authority would decide who, if anyone, to proceed against.

It would do so strictly according to its legal obligations.

He declined to comment on whether charges might be brought against Zuma, who has been implicated in documents, which appear to suggest he solicited a bribe from French company Thales.

But he did say the cases could well "test the maturity of our democracy".

Zuma has on several occasions claimed his innocence of the allegations against him.

With acknowledgements to Tim Cohen and the Business Day.